Transducer devices and methods for hearing

ABSTRACT

A device to transmit an audio signal to a user may comprise a mass, a piezoelectric transducer, and a support to support the mass and the piezoelectric transducer with the eardrum. The piezoelectric transducer can be configured to drive the support and the eardrum with a first force and the mass with a second force opposite the first force. The device may comprise circuitry configured to receive wireless power and wireless transmission of an audio signal, and the circuitry can be supported with the eardrum to drive the transducer in response to the audio signal, such that vibration between the circuitry and the transducer can be decreased. The transducer can be positioned away from the umbo of the ear to drive the eardrum, for example on the lateral process of the malleus.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of PCT/US2009/057716 (AttorneyDocket No. 026166-002010PC), filed Sep. 22, 2009, which claims priorityto U.S. Patent Application Nos.; 61/139,526 filed Dec. 19, 2008(Attorney Docket No. 026166-002300US, entitled “Balanced ArmatureDevices and Methods for Hearing”; 61/217,801 filed on Jun. 3, 2009(Attorney Docket No. 026166-002310US); 61/099,087 filed Sep. 22, 2008(Attorney Docket No. 026166-002000US), entitled “Transducer Devices andMethods for Hearing”; and 61/109,785 filed Oct. 30, 2008 (AttorneyDocket No. 026166-002010US), entitled “Transducer Devices and Methodsfor Hearing”; the full disclosures of which are incorporated herein byreference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

This invention was supported by grants from the National Institutes ofHealth (Grant No. R.44DC008499-02A1). The Government may have certainrights in this invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention is related to hearing systems, devices andmethods. Although specific reference is made to hearing aid systems,embodiments of the present invention can be used in many applications inwhich a signal is used to stimulate the ear.

People like to hear. Hearing allows people to listen to and understandothers. Natural hearing can include spatial cues that allow a user tohear a speaker, even when background noise is present.

Hearing devices can be used with communication systems to help thehearing impaired. Hearing impaired subjects need hearing aids toverbally communicate with those around them. Open canal hearing aidshave proven to be successful in the marketplace because of increasedcomfort and an improved cosmetic appearance. Another reason why opencanal hearing aides can be popular is reduced occlusion of the earcanal. Occlusion can result in an unnatural, tunnel-like hearing effectwhich can be caused by large hearing aids which block the ear canal. Inat least some instances, occlusion be noticed by the user when he or shespeaks and the occlusion results in an unnatural sound during speech.However, a problem that may occur with open canal hearing aids isfeedback. The feedback may result from placement of the microphone intoo close proximity with the speaker or the amplified sound being toogreat. Thus, feedback can limit the degree of sound amplification that ahearing aid can provide. Although feedback can be decreased by placingthe microphone outside the ear canal, this placement can result in thedevice providing an unnatural sound that is devoice of the spatiallocation information cues present with natural hearing.

In some instances, feedback may be decreased by using non-acoustic meansof stimulating the natural hearing transduction pathway, for examplestimulating the tympanic membrane, bones of the ossicular chain and/orthe cochlea. An output transducer may he placed on the eardrum, theossicles in the middle ear, or the cochlea to stimulate the hearingpathway. Such an output transducer may be electro magnetically based.For example, the transducer may comprise a magnet and coil placed on theossicles to stimulate the hearing pathway. Surgery is often needed toplace a hearing device on the ossicles or cochlea, and such surgery canbe somewhat invasive in at least some instances. At least some of theknown methods of placing an electromagnetic transducer on the eardrummay result in occlusion in some instances.

One promising approach has been to place a magnet on the eardrum anddrive the magnet with a coil positioned away from the eardrum. Themagnets can be electromagnetically driven with a coil to cause motion inthe hearing transduction pathway thereby causing neural impulses leadingto the sensation of hearing. A permanent magnet may be coupled to theear drum through the use of a fluid and surface tension, for example asdescribed in U.S. Pat. Nos. 5,259,032 and 6,084,975.

However, there is still room for improvement. For example, with a magnetpositioned on the eardrum and coil positioned away from the magnet, thestrength of the magnetic field generated to drive the magnet maydecrease rapidly with the distance from the driver coil to the permanentmagnet. Because of this rapid decrease in strength over distance,efficiency of the energy to drive the magnet may be less than ideal.Also, placement of the driver coil near the magnet may cause discomfortfor the user in some instances. There can also be a need to align thedriver coil with the permanent magnet that may, in some instances, causethe performance to be less than ideal.

For the above reasons, it would be desirable to provide hearing systemswhich at least decrease, or even avoid, at least some of the abovementioned limitations of the current hearing devices. For example, thereis a need to provide a comfortable hearing device which provides hearingwith natural qualities, for example with spatial information cues, andwhich allow the user to hear with less occlusion, distortion andfeedback than current devices.

2. Description of the Background Art.

Patents and publications that may be relevant to the present applicationinclude: U.S. Pat. Nos. 3,585,416; 3,764,748; 3,882,285; 5,142,186;5,554,096; 5,624,376; 5,795,287; 5,800,336; 5,825,122; 5,857,958;5,859,916; 5,888,187; 5,897,486; 5,913,815; 5,949,895; 6,005,955;6,068,590; 6,093,144; 6,139,488; 6,174,278; 6,190,305; 6,208,445;6,217,508; 6,222,302; 6,241,767; 6,422,991; 6,475,134; 6,519,376;6,620,110; 6,626,822; 6,676,592; 6,728,024; 6,735,318; 6,900,926;6,920,340; 7,072,475; 7,095,981; 7,239,069; 7,289,639; D512,979;2002/0086715; 2003/0142841; 2004/0234092; 2005/0020873; 2006/0107744;2006/0233398; 2006/075175; 2007/0083078; 2007/0191673; 2008/0021518;2008/0107292; commonly owned U.S. Pat. No. 5,259,032 (Attorney DocketNo. 026166-000500US); U.S. Pat. No. 5,276,910 (Attorney Docket No.026166-000600US); U.S. Pat. No. 5,425,104 (Attorney Docket No.026166-000700US); U.S. Pat. No. 5,804,109 (Attorney Docket No.026166-000200US); U.S. Pat. No. 6,084,975 (Attorney Docket No.026166-000300US); U.S. Pat. No. 6,554,761 (Attorney Docket No.026166-001700US); U.S. Pat. No. 6,629,922 (Attorney Docket No.026166-001600US); U.S. Publication Nos. 2006/0023908 (Attorney DocketNo. 026166-000100US); 2006/0189841 (Attorney Docket No.026166-000820US); 2006/0251278 (Attorney Docket No. 026166-000900US);and 2007/0100197 (Attorney Docket No. 026166-001100US). Non-U.S. patentsand publications that may be relevant include EP1845919 PCT PublicationNos. WO 03/063542; WO 2006/075175; U.S. Publication Nos. Journalpublications that may be relevant include: Ayatollahi et al., “Designand Modeling of 114 Micromachines Condenser MEMS Loudspeaker usingPermanent Magnet Neodymium-Iron-Boron (Nd—Fe—B)”, ISCE, Kuala Lampur,2006; Birch et al, “Microengineered Systems for the Hearing Impaired”,IEE, London, 1996; Cheng et al., “A silicon microspeaker for hearinginstruments”, J. Micromech. Microeng., 14(2004) 859-866; Yi et al.,“Piezoelectric microspeaker with compressive nitride diaphragm”, IEEE,2006, and Zhigang Wang et al., “Preliminary Assessment of RemotePhotoelectric Excitation of an Actuator for a Hearing Implant”, IEEEEngineering in Medicine and Biology 27th Annual Conference, Shanghai,China, Sep. 1-4, 2005. Other publications of interest include: GennumGA3280 Preliminary Data Sheet, “Voyager TD™ Open Platform DSP System forUltra Low Power Audio Processing” and National Semiconductor LM4673 DataSheet, “LM4673 Filterless, 2.65W, Mono, Class D audio Power Amplifier”;Puria, S. et al., Middle ear morphometry from cadaveric temporal bonemicroCT imaging, Invited Talk. MEMRO 2006, Zurich; Puria, S. et al, Agear in the middle ear ARO 2007, Baltimore, Md.

BRIEF SUMMARY OF THE INVENTION

The present invention is related to hearing systems, devices andmethods. Although specific reference is made to hearing aid systems,embodiments of the present invention can be used in many applications inwhich a signal is used to stimulate the ear.

Embodiments of the present invention can provide improved hearing whichovercomes at least some of the aforementioned limitations of currentsystems. In many embodiments, a device to transmit an audio signal to auser may comprise a transducer assembly comprising a mass, apiezoelectric transducer, and a support to support the mass and thepiezoelectric transducer with the eardrum. The piezoelectric transducercan be configured to drive the support and the eardrum with a firstforce and the mass with a second force opposite the first force. Thisdriving of the ear drum and support with a force opposite the mass canresult in more direct driving of the eardrum, and can improve couplingof the vibration of transducer to the eardrum. The transducer assemblydevice may comprise circuitry configured to receive wireless power andwireless transmission of an audio signal, and the circuitry can besupported with the eardrum to drive the transducer in response to theaudio signal, such that vibration between the circuitry and thetransducer can be decreased. The wireless signal may comprise anelectromagnetic signal produced with a coil, or an electromagneticsignal comprising light energy produce with a light source. In at leastsome embodiments, at least one of the transducer or the mass can bepositioned on the support away from the umbo of the ear when the supportis coupled to the eardrum to drive the eardrum, so as to decrease motionof the transducer and decrease user perceived occlusion, for examplewhen the user speaks. This positioning of the transducer and/or the massaway from the umbo, for example on the short process of the malleus, mayallow a transducer with a greater mass to be used and may even amplifythe motion of the transducer with the malleus. In at least someembodiments, the transducer may comprise a plurality of transducers todrive the malleus with both a hinging rotational motion and a twistingmotion, which can result in more natural motion of the malleus and canimprove transmission of the audio signal to the user.

In a first aspect, embodiments of the present invention provide a deviceto transmit an audio signal to a user. The user has an ear comprising anear drum. The device comprises a mass, a piezoelectric transducer, and asupport to support the mass and the piezoelectric transducer with theeardrum. The piezoelectric transducer is configured to drive the supportand the eardrum with a first force and the mass with a second forceopposite the first force.

In many embodiments, the piezoelectric transducer is disposed betweenthe mass and the support.

In many embodiments, the device further comprises at least one flexiblestructure disposed between the piezoelectric transducer and the mass.

In many embodiments, the piezoelectric transducer is magneticallycoupled to the support.

In many embodiments, the piezoelectric transducer comprises a firstportion connected to the mass and a second portion connected to thesupport to drive the mass opposite the support.

In many embodiments, the support comprises a first side shaped toconform with the eardrum. A protrusion can be disposed opposite thefirst side and affixed to the piezoelectric transducer.

In many embodiments, the device further comprises a fluid disposedbetween the first side and the eardrum to couple the support to theeardrum. The fluid may comprise a liquid composed of at least one of anoil, a mineral oil, a silicone oil or a hydrophobic liquid. In someembodiments, the support comprises a second side disposed opposite thefirst side and the protrusion extends from the second side to thepiezoelectric transducer.

In many embodiments, the support comprises a first component and asecond component. The first component may comprise a flexible materialshaped to conform to the eardrum and flex with motion of the eardrum.The second component may comprise a rigid material extending from thetransducer to the flexible material to transmit the first force to theflexible material and the eardrum. In at least some embodiments, therigid material comprises at least one of a metal, titanium, a stainlesssteel or a rigid plastic, and the flexible material comprises at leastone of a silicone, a flexible plastic or a gel.

In many embodiments, the device further comprises a housing, the housingrigidly affixed to the mass to move the housing and the mass oppositethe support. In some embodiments, the support comprises a rigid materialthat extends through the housing to the transducer to move the mass andthe housing opposite the support.

In many embodiments, the mass comprises circuitry coupled to thetransducer and supported with the support and the transducer. Thecircuitry is configured to receive wireless power and wirelesstransmission of the audio signal to drive the transducer in response tothe audio signal.

In many embodiments, the piezoelectric transducer comprises at least oneof a piezoelectric unimorph transducer, a bimorph-bender piezoelectrictransducer, a piezoelectric multimorph transducer, a stackedpiezoelectric transducer with a mechanical multiplier or a ringpiezoelectric transducer with a mechanical multiplier.

In some embodiments, the piezoelectric transducer comprises thebimorph-bender piezoelectric transducer and the mass comprises a firstmass and a second mass. The bimorph bender comprises a cantileverextending from a first end supporting the first mass to a second endsupporting the second mass. The support is coupled to the cantileverbetween the first end and the second end to drive the ear drum with thefirst force and drive the first mass and the second mass with the secondforce.

In some embodiments, the piezoelectric transducer comprises the stackedpiezoelectric transducer with the mechanical multiplier. The mechanicalmultiplier comprises a first side coupled to the support to drive theeardrum with the first force and a second side coupled to the mass todrive the mass with the second force.

In some embodiments, the piezoelectric transducer comprises the ringpiezoelectric transducer with the mechanical multiplier. The mechanicalmultiplier comprises a first side and a second side. The first sideextends inwardly from the ring piezoelectric transducer to the mass. Thesecond side extends inwardly toward a protrusion of the support. Themass moves away from the protrusion of the support when the ringcontracts and toward the protrusion of the support when the ringexpands. The ring piezoelectric multiplier may define a center havingcentral axis extending there through. The central protrusion and themass may be disposed along the central axis.

In some embodiments, the piezoelectric transducer comprises the bimorphbender. The mass comprises a ring having a central aperture formedthereon. The bimorph bender extends across the ring with a first end anda second end coupled to the ring. The support extends through theaperture and connects to the piezoelectric transducer between the firstend and the second end to move the support opposite the ring when thebimorph bender bends. The bimorph bender can be connected to the ringwith an adhesive on the first end and the second end such that the firstend and the second end are configured to move relative to the ring withshear motion when the bimorph bender bends to drive the support oppositethe ring.

In another aspect, embodiments of the present invention provide a deviceto transmit an audio signal to a user. The user has an ear comprising aneardrum. The device comprises a transducer, circuitry coupled to thetransducer, and a support configured to couple to the eardrum andsupport the circuitry and the transducer with the eardrum. The circuitryis configured to receive at least one of wireless power or wirelesstransmission of the audio signal to drive the transducer in response tothe audio signal.

In many embodiments, the transducer is configured to drive the supportand the eardrum with a first force and drive the circuitry with a secondforce opposite the first force.

In many embodiments, the circuitry is rigidly attached to a mass andcoupled to the transducer to drive the circuitry and the mass with thefirst force. In some embodiments, the circuitry is rigidly attached tothe mass and coupled to the transducer to drive the circuitry and themass with the second force.

In many embodiments, the circuitry is flexibly attached to a mass andcoupled to the transducer to drive the circuitry and the mass with thefirst force. In some embodiments, the circuitry is flexibly attached tothe mass and coupled to the transducer to drive the circuitry and themass with the second force.

In many embodiments, the circuitry comprises at least one of aphotodetector or a coil supported with the support and coupled to thetransducer to drive the transducer with the at least one of the wirelesspower or wireless transmission of the audio signal.

In many embodiments, the transducer comprises at least one of apiezoelectric transducer, a magnetostrictive transducer, a magnet or acoil.

In another aspect, embodiments of the invention provide a device totransmit an audio signal to a user. The user has an ear comprising aneardrum having a mechanical impedance. The device comprises a transducerand a support to support the transducer with the eardrum. A combinedmass of the support and the transducer supported thereon is configuredto match the mechanical impedance of the eardrum for at least oneaudible frequency between about 0.8 kHz and about 10 kHz.

In many embodiments, the combined mass comprises no more than about 50mg. In some embodiments, the combined mass is within a range from about10 mg to about 40 mg.

In many embodiments, the combined mass comprises at least one of a massfrom circuitry to drive the transducer, a mass from a housing disposedover the transducer or a metallic mass coupled to the transduceropposite the support. In some embodiments, the transducer, the circuitryto drive the transducer, the housing disposed over the transducer andthe metallic mass are supported with the eardrum when the support iscoupled to the eardrum.

In many embodiments, at least one audible frequency is between about 1kHz and about 6 KHz.

In many embodiments, the transducer and the mass are positioned on thesupport to place at least one of the transducer or the mass away from anumbo of the eardrum when the support is placed on the eardrum. Thispositioning can decrease a mechanical impedance of the support to soundtransmitted with the eardrum When the support is positioned on theeardrum.

In many embodiments, the piezoelectric transducer comprises a stiffness.The stiffness of the piezoelectric transducer is matched to themechanical impedance of the eardrum for the at least one audiblefrequency.

In many embodiments, the eardrum comprises an umbo and the acousticinput impedance comprises an acoustic impedance of the umbo. Thestiffness of the piezoelectric transducer is matched to the acousticinput impedance of the umbo.

In another aspect, embodiments of the present invention provide a deviceto transmit an audio signal to a user. The user has an ear comprising aneardrum and a malleus connected to the ear drum at an umbo. The devicecomprises a transducer and a support to support the transducer with theeardrum. The transducer is configured to drive the eardrum. Thetransducer is positioned on the support to extend away from the umbowhen the support is placed on the eardrum.

In many embodiments, a mass is positioned on the support for placementaway from the umbo when the support is placed against the eardrum, andthe transducer extends between the mass arid a position on the supportthat corresponds to the umbo so as to couple vibration of the transducerto the umbo. The mass can be positioned on the support to align the masswith the malleus away from the umbo when the support is placed againstthe eardrum.

In many embodiments, the transducer is positioned on the support so asto decrease a first movement of the transducer relative to a secondmovement of the umbo when the eardrum vibrates and to amplify the secondmovement of the umbo relative to the first movement of the transducerwhen the transducer vibrates. In some embodiments, the first movement ofthe transducer is no more than about 75% of the second movement of theumbo and the second movement of the umbo is at least about 25% more thanthe first movement of the transducer. The first movement of thetransducer may be no more than about 67% of the second movement of theumbo and the second movement of the umbo may be at least about 50% morethan the first movement of the transducer.

In many embodiments, the device further comprises a mass, and thetransducer is disposed between the mass and the support.

In many embodiments, the support is shaped to the eardrum of the user toposition the support on the eardrum in a predetermined orientation. Thetransducer is positioned on the support to align the transducer with amalleus of the user with the eardrum disposed between the malleus andthe support when the support is placed on the eardrum. In someembodiments, the support comprises a shape from a mold of the eardrum ofthe user.

In many embodiments, the transducer is positioned on the support toplace the transducer away from a tip of the malleus when the support isplaced on the eardrum.

In many embodiments, the transducer is positioned on the support toplace the transducer away from the tip when the support is positioned onthe eardrum. The malleus comprises a head and a handle. The handleextends from the head to a tip near the umbo of the eardrum.

In many embodiments, the transducer is positioned on the support toalign the transducer with the lateral process of the malleus with theeardrum disposed between the lateral process and the support when thesupport is placed on the eardrum. In some embodiments, the supportcomprises a rigid material that extends from the transducer toward thelateral process to move the lateral process opposite the mass.

In many embodiments, the transducer comprises at least one of apiezoelectric transducer, a magnetostrictive transducer, aphotostrictive transducer, a coil or a magnet.

In many embodiments, the transducer comprises the piezoelectrictransducer. The piezoelectric transducer may comprise a cantileveredbimorph bender, which has a first end anchored to the support and asecond end attached to a mass to drive the mass opposite the lateralprocess when the support is placed on the eardrum.

In many embodiments, the device further comprises a mass coupled to thetransducer and circuitry coupled to the transducer to drive thetransducer. The mass and the circuitry is supported with the eardrumwhen the support is placed on the ear. The support, the transducer, themass and the circuitry comprise a combined mass of no more than about 60mg, for example, a combined mass of no more than about 40 mg or even acombined mass of no more than 30 mg.

In another aspect, embodiments of the present invention provide a deviceto transmit an audio signal to a user. The user has an ear comprising anear drum. The device comprises a first transducer, a second transducer,and a support to support the first transducer and the second transducerwith the eardrum when the support is placed against the eardrum. Thefirst transducer is positioned on the support to couple to a first sideof the malleus. The second transducer positioned on the support tocouple to a second side of the malleus.

In many embodiments, the first transducer is positioned on the supportto couple to the first side of the malleus and the second transducer ispositioned on the support to coupled to the second side of the malleuswhich is opposite the first side of the malleus.

In many embodiments, the support comprises a first protrusion extendingto the first transducer to couple the first side of the malleus to thefirst transducer and a second protrusion extending to the secondtransducer to couple the second side of the malleus to the secondtransducer.

In many embodiments, the first transducer and second transducer arepositioned on the support and configured to twist the malleus with afirst rotation about a longitudinal axis of the malleus when the firsttransducer and second transducer move in opposite directions. The firsttransducer and second transducer can be positioned on the support andconfigured to rotate the malleus with a second hinged rotation when thefirst transducer and second transducer move in similar directions.

In many embodiments, the device further comprises circuitry coupled tothe first transducer and the second transducer. The circuitry isconfigured to generate a first signal to drive the transducer and asecond signal to drive the second transducer. In some embodiments, thecircuitry is configured to generate the first signal at least partiallyout of phase with the second signal and drive the malleus with atwisting motion. The circuitry can be configured to drive the firsttransducer substantially in phase with the second transducer at a firstfrequency below about 1 kHz, and the circuitry can be configured todrive the first transducer at least about ten degrees out of phase withthe second transducer at a second frequency above at least about 2 kHz.

In many embodiments, the first transducer comprises at least one of afirst piezoelectric transducer, a first coil and magnet transducer, afirst magnetostrictive transducer or a first photostrictive transducer,and the second transducer comprises at least one of a secondpiezoelectric transducer, a second coil and magnet transducer, a secondmagnetostrictive transducer or a second photostrictive transducer.

In another aspect, embodiments of the present invention provide a methodof transmitting an audio signal to a user. The user has an earcomprising an eardrum. The method comprises supporting a mass and apiezoelectric transducer with a support on the eardrum of the user anddriving the support and the eardrum with a first force and the mass witha second force, the second force opposite the first force.

In many embodiments, the ear comprises a mechanical impedance. The mass,the piezoelectric transducer and the support comprise a combinedmechanical impedance. The combined mechanical impedance matches themechanical impedance of the eardrum for at least one audible frequencywithin a range from about 1 kHz to about 6 KHz.

In another aspect, embodiments of the present invention provide a methodof transmitting an audio signal to a user. The user has an earcomprising an eardrum. The method comprises supporting circuitry and atransducer coupled to the circuitry with the eardrum and transmittingthe audio signal with a wireless signal to the circuitry to drive thetransducer in response to the audio signal.

In another aspect, embodiments of the present invention provide a methodof transmitting an audio signal to a user. The user has an earcomprising an eardrum having a mechanical impedance. The methodcomprises supporting a transducer and a support coupled to the eardrumwith the eardrum. A combined mass of the support and the transducersupported thereon matches the mechanical impedance of the eardrum for atleast one audible frequency between about 0.8 kHz and about 10 kHz.

In another aspect, embodiments of the present invention provide a methodof transmitting an audio signal to a user. The user has an earcomprising an eardrum and a malleus connected to the ear drum at anumbo. The method comprises supporting a transducer with a supportpositioned on the eardrum and vibrating the support and the eardrum withthe transducer positioned away from the umbo. In many embodiments, afirst movement of the transducer is decreased relative to a secondmovement of the umbo when the eardrum is vibrated and the secondmovement of the umbo is amplified relative to the first movement of thetransducer.

In another aspect, embodiments of the present invention provide a methodof transmitting an audio signal to a user. The user has an earcomprising an eardrum and a malleus connected to the eardrum at an umbo.The method comprises supporting a first transducer and a secondtransducer with a support positioned on the eardrum. The firsttransducer and the second transducer are driven in response to the audiosignal to the twist the malleus such that the malleus rotates about anelongate longitudinal axis of the malleus.

BRIEF DESCRIPTION OF THE DRAWINGS

A hearing aid system using wireless signal transduction is shown in FIG.1, according to embodiments of the present invention;

FIG. 1A shows the lateral side of the eardrum and FIG. 1B shows themedial side of the eardrum, suitable for incorporation of the hearingaid system of FIG. 1;

FIGS. 1C and 1D show the eardrum coupled to the ossicles including themalleus, incus, and stapes, and locations of attachment for the hearingaid system shown in FIG. 1;

FIG. 2 shows the sensitivity of silicon photovoltaics to differentwavelengths of light, suitable for incorporation with the system ofFIGS. 1A to 1D;

FIG. 3 shows the mechanical impedance of the eardrum in relation to thatof various masses, in accordance with the system of FIGS. 1A to 2;

FIG. 4 shows a simply supported bimorph bender, in accordance with thesystems of FIGS. 1A to 3;

FIG. 5A shows a cantilevered bimorph bender, in accordance with thesystem of FIGS. 1A to 3;

FIG. 5B shows cantilevered bimorph bender which includes a first massand a second mass, in accordance with the system of FIGS. 1A to 3;

FIG. 6 shows a stacked piezo with mechanical multiplier, in accordancewith the system of FIGS. 1A to 3;

FIG. 7 shows a narrow ring piezo with a mechanical multiplier, inaccordance with the system of FIGS. 1A to 3;

FIG. 8 shows a ring mass with bimorph piezo, in accordance with thesystem of FIGS. 1A to 3;

FIGS. 8A and 8B show a cross-sectional view and a top view,respectively, of a ring mass with bimorph piezo, in accordance with thesystem of FIGS. 1A to 3;

FIGS. 8B1 and 8B2 shows a perspective view of ring mass with a bimorphpiezo with flexible structures to couple the bimorph piezo to the ringmass, in accordance with the system of FIGS. 1A to 3;

FIGS. 8C and 8D show a cross-sectional view and a top view,respectively, of a ring mass with dual bimorph piezo, in accordance withthe systems of FIGS. 1A to 3;

FIG. 8E shows a plot of phase difference versus frequency for the firstand second transducers of the dual bimorph piezo of FIGS. 8C and 8D;

FIG. 9 shows a simply supported bimorph bender with a housing, inaccordance with the systems of FIGS. 1A to 4;

FIG. 9A shows an optically powered output transducer, in accordance withthe systems of FIGS. 1A to 3;

FIG. 9B shows a magnetically powered output transducer, in accordancewith the systems of FIGS. 1A to 3;

FIG. 10 shows a cantilevered bimorph bender placed on the eardrum awayfrom the umbo and on the lateral process, in accordance with the systemsof FIGS. 1A to 3;

FIG. 10A shows an output transducer assembly comprising a cantileveredbimorph bender placed on the ear drum with a mass on the lateral processaway from the umbo and an elongate member comprising a cantileverextending from the mass toward the Limbo so as to couple to the eardrumat the umbo, in accordance with the systems of FIGS. 1A to 3;

FIG. 10B shows the cantilevered bimorph bender of FIG. 10A from anotherview;

FIG. 11 shows a side view of a transducer comprising two cantileveredbimorph benders placed on different locations on the eardrum, inaccordance with the systems of FIGS. 1A to 3;

FIG. 11A shows two cantilevered bimorph benders placed on the ear drumover the umbo and the lateral process, in accordance with the systems ofFIGS. 1A to 3;

FIG. 12 shows an exemplary graph of simulation results for an outputtransducers in accordance with the systems of FIGS. 1A to 3;

FIG. 13A shows a stacked piezo and FIG. 13B shows a plot of displacementper voltage for the stacked piezo of FIG. 13A;

FIG. 14A shows a series bimorph and FIG. 14B shows a plot ofdisplacement per voltage for the series bimorph of FIG. 14A;

FIG. 15A shows a single crystal bimorph cantilever and FIG. 15B shows aplot o displacement per voltage for the single crystal bimorphcantilever of FIG. 15A;

FIG. 16A shows a bimorph on a washer and FIG. 16B shows a plot ofdisplacement per voltage for the bimorph on a washer of FIG. 16A;

FIG. 17A shows a stacked piezo pair, FIG. 17B shows a plot ofdisplacement per voltage for the stacked piezo pair of FIG. 17A, andFIG. 17C shows a plot of lever ratio for the stacked piezo pair of FIG.17C;

FIG. 18A shows a plot of peak output for a bimorph piezo placed on theLimbo, and FIG. 18B shows a plot of feedback for a bimorph piezo placedon the umbo;

FIG. 19A shows a plot of peak output for a bimorph piezo placed on thecenter of pressure on an eardrum, and FIG. 19B shows a plot of feedbackfor a biomorph piezo placed on the center of pressure on an eardrum; and

FIG. 20A shows a plot of peak output for a stacked piezo placed on thecenter of pressure on an eardrum, and FIG. 20B shows a plot of feedbackfor a stacked piezo placed on the center of pressure on an eardrum.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention can provide optically coupledhearing devices with improved audio signal transmission. The systems,devices, and methods described herein may find application for hearingdevices, for example open ear canal hearing aides. Although specificreference is made to hearing aid systems, embodiments of the presentinvention can be used in any application in which a signal is wirelesslyreceived and converted into a mechanical output.

As used herein, the umbo of the eardrum encompasses a portion of theeardrum that extends most medially along the ear canal, so as to includea tip, or vertex of the ear canal. As used herein, a twisting motionand/or twisting encompass a rotation of an elongate body about anelongate axis extending along the elongate body, for example rotation ofa rigid elongate bone about an elongate axis of the bone. Twisting asused herein encompasses rotation of the elongate body both with torsionof the elongate body about the elongate axis and also without torsion ofthe elongate body about the elongate axis. As used herein torsionencompasses a strain, or deformation, that can occur with twisting, suchthat one part of the elongate body twists, or rotates, more than anotherpart of the elongate body.

FIG. 1 shows a hearing aid system using wireless signal transduction.The hearing system 10 includes an input transducer assembly 20 and anoutput transducer assembly 30. Hearing system 10 may comprise a behindthe ear unit BTE. Behind the ear unit BTE may comprise many componentsof system 10 such as a speech processor, battery, wireless transmissioncircuitry and input transducer assembly 10. Behind the ear unit BTE maycomprise many component as described in U.S. Pat. Pub. Nos.2007/0100197, entitled “Output transducers for hearing systems”; and2006/0251278, entitled “Hearing system having improved high frequencyresponse”. The input transducer assembly 20 is located at leastpartially behind the pinna P, although an input transducer assembly maybe located at many sites such as in pinna P or entirely within ear canalEC. The input transducer assembly 20 can receive a sound input, forexample an audio sound. With hearing aids for hearing impairedindividuals, the input can be ambient sound. The input transducerassembly comprises an input transducer, for example a microphone 22.Microphone 22 can be positioned in many locations such as behind theear, if appropriate. Microphone 22 is shown positioned within ear canalnear the opening to detect spatial localization cues from the ambientsound. The input transducer assembly can include a suitable amplifier orother electronic interface. In some embodiments, the input may comprisean electronic sound signal from a sound producing or receiving device,such as a telephone, a cellular telephone, a Bluetooth connection, aradio, a digital audio unit, and the like.

Input transducer assembly 20 includes a signal output source 12 whichmay comprise an electromagnetic source such as a light source such as anLED or a laser diode, an electromagnet, an RF source, or the like.Alternatively, an amplifier of the input assembly may be coupled to theoutput transducer assembly with a conductor such as a flexible wire,conductive trace on a flex printed circuitry board, or the like. Thesignal output source can produce an output signal based on the soundinput. Output transducer assembly 30 can receive the output sourcesignal and can produce mechanical vibrations in response. Outputtransducer assembly 30 may comprise a transducer responsive to theelectromagnetic signal, for example at least one photodetector, a coilresponsive to the electromagnet, a magenetostrictve element, aphotostrictive element, a piezoelectric element, or the like. Whenproperly coupled to the subject's hearing transduction pathway, themechanical vibrations caused by output transducer assembly 30 can induceneural impulses in the subject which can be interpreted by the subjectas the original sound input.

The output transducer assembly 30 can be configured to couple to a pointalong the hearing transduction pathway of the subject in order to induceneural impulses which can be interpreted as sound by the subject. Asshown in FIG. 1, the output transducer assembly 30 may be coupled to thetympanic membrane or eardrum TM. Output transducer assembly 30 may besupported on the eardrum TM by a support, housing, mold, or the likeshaped to conform with the shape of the eardrum TM. A fluid may bedisposed between the eardrum TM and the output transducer assembly 30such as an oil, a mineral oil, a silicone oil, a hydrophobic liquid, orthe like. Output transducer assembly 30 can cause the eardrum TM to movein a first direction 40 and in a second direction 45 opposite the firstdirection 40, such that output transducer assembly 30 may cause theeardrum TM to vibrate. Specific points of attachment are described inprior U.S. Pat. Nos. 5,259,032; and 6,084,975, the full disclosures ofwhich are incorporated herein by reference and may be suitable forcombination with some embodiments of the present invention,

FIG. 1A shows structures of the ear suitable for placement of the outputtransducer assembly from the lateral side of the eardrum TM, and FIG. 1Bshows structures of the ear from the medial side of the eardrum TM. Theeardrum TM is connected to a malleus ML. Malleus ML comprises a head H,a manubrium MA, a lateral process LP, and a tip T. Manubrium MA isdisposed between head H and tip T and coupled to eardrum TM, such thatthe malleus ML vibrates with vibration of eardrum TM.

FIG. 1C. shows output transducer assembly 30 coupled to the eardrum TMon the umbo UM to transmit vibration so that the user can perceivesound. Eardrum TM is coupled to the ossicles including the malleus ML,incus IN, and stapes ST. The manubrium MA of the malleus ML can befirmly attached to eardrum TM. The most depressed or concaved point ofthe eardrum TM comprises the umbo UM. Malleus ML comprises a first axis110, a second axis 113 and a third axis 115. Incus IN comprises a firstaxis 120, a second axis 123 and a third axis 125. Stapes ST comprises afirst axis 130, a second axis 133 and a third axis 135.

The axes of the malleus ML, incus IN and stapes ST can be defined basedon moments of inertia. The first axis may comprise a minimum moment ofinertia for each bone. The second axis comprises a maximum moment ofinertia for each bone. The first axis can be orthogonal to the secondaxis. The third axis extends between the first and second axes, forexample such that the first, second and third axes comprise a righthanded triple. For example first axis 110 of malleus ML may comprise theminimum moment of inertia of the malleus. Second axis 113 of malleus MLmay comprise the maximum moment of inertia of malleus ML. Third axis 115of malleus ML can extend perpendicular to the first and second axis, forexample as the third component of a right handed triple defined by firstaxis 110 and second axis 113. Further first axis 120 of incus IN maycomprise the minimum moment of inertia of the incus. Second axis 123 ofincus IN may comprise the maximum moment of inertia of incus IN. Thirdaxis 125 of incus IN can extend perpendicular to the first and secondaxis, for example as the third component of a right handed tripledefined by first axis 120 and second axis 123. First axis 130 of stapesST may comprise the minimum moment of inertia of the stapes. Second axis133 of stapes ST may comprise the maximum moment of inertia of stapesST. Third axis 135 of stapes ST can extend perpendicular to the firstand second axis, for example as the third component of a right handedtriple defined by first axis 130 and second axis 133.

Vibration of the output transducer system induces vibration of eardrumTM and malleus ML that is transmitted to stapes ST via Incus IN, suchthat the user perceives sound. Low frequency vibration of eardrum TM atumbo UM can cause hinged rotational movement 125A of malleus ML andincus IN about axis 125. Translation at umbo UM and causes a hingedrotational movement 125B of the tip T of malleus ML and hingedrotational movement 125A of malleus ML and incus IN about axis 125,which causes the stapes to translate along axis 135 and transmitsvibration to the cochlea. Vibration of eardrum TM, for example at higherfrequencies, may also cause malleus ML to twist about elongate firstmalleus axis 110 in a twisting movement 110A. Such twisting may comprisetwisting movement 110B on the tip T of the malleus ML. The twisting ofmalleus ML about first malleus axis 110 may cause the incus IN to twistabout first incus axis 120. Such rotation of the incus can cause thestapes to transmit the vibration to the cochlea where the vibration isperceived as sound by the user.

With the output transducer assembly positioned over the eardrum TM onthe umbo UM, the combined mass of the output transducer assembly can befrom about 10 to about 60 mg, for example from about 10 to about 40 mg.In some embodiments, the combined mass comprises no more than about 50mg. The combined mass may comprise the mass of the support, thetransducer, a mass opposite the support and/or the circuitry to receivea wireless signal and drive the transducer. The support can beconfigured to support the transducer, a mass opposite the support and/orthe circuitry to receive a wireless signal and drive the transducer withthe eardrum when the support is placed against the eardrum.

FIG. 1D shows output transducer assembly 30 coupled on the TM away fromumbo UM, for example over the lateral process LP of the malleus ML.Output transducer assembly 30 may be placed on other parts of theeardrum as well. Depending on the placement of output transducerassembly 30 on the eardrum TM, the mechanical impedance of the outputtransducer assembly 30 and the eardrum TM may vary. Placement of outputtransducer assembly 30 away from the umbo UM allows for increased massof the lateral process while minimizing occlusion. For example, withplacement over the lateral process, the mass of the output transducerassembly may comprise approximately twice the mass as when placed overthe umbo without causing occlusion. For example, an output transducerassembly comprising a mass of 60 mg positioned over the lateral processwill provide a mechanical impedance and occlusion similar to a 30 mgmass positioned over the umbo. Further the vibration of the transducerat the lateral process is amplified from the lateral process to theumbo, for example by a factor of two due to leverage of the malleus withhinged rotation from the head of the malleus to the tip near the umbo.

The mass of transducer assembly 30 for placement away from the umbo canbe similar to ranges described above for the configuration placed overthe umbo, and may be scaled accordingly. For example, with the outputtransducer assembly positioned over the eardrum TM away from the umboUM, for example over the lateral process, the combined mass of theoutput transducer assembly can be from about 20 to about 120 mg, forexample from about 40 to about 80 mg. In many embodiments, the combinedmass of output transducer assembly 30 over the lateral process can befrom about 20 mg to about 60 mg to provide occlusion and transmissionlosses similar to a mass of about 10 mg to about 30 mg over the umbo.

Output transducer assembly 30 may have a number of exemplaryspecifications for maximum output. Output transducer assembly 30 mayproduce a sound pressure level of up to 106 dB. For example, a soundpressure level of up to at least about 90 dB can be sufficient toprovide quality hearing for many hearing impaired users. The “center” ofthe eardrum, or the umbo, may move at 0.1 um/Pa at 1 kHz and 0.01 um/Paat 10 kHz. The velocity can be 630 um/s/Pa from about 1 kHz and 10 kHz.The area of the eardrum may be about 100 mm². The ear drum may have animpedance of about 0.2 Ns/m for frequencies greater than 1 kHz, whichmay be damping in nature, and an impedance of about 1000 N/m forfrequencies less than 1 kHz in nature, which may be stiffening innature. Thus, the power input into the ear at up to 106 dB SPL may be upto about 1 uW.

Output transducer assembly 30 may comprise a number of exemplaryspecifications for frequency response. Output transducer assembly 30 canhave a frequency response of 100 Hz to 10 kHz. For an open canal system,it may be acceptable if low frequency response rolls off below 1 kHzsince most hearing impaired subjects have relatively good low frequencyhearing and the natural sound pathway can provide this portion of thesound spectrum. A relatively flat response may be good and it may beideal if a resonance is generated at 2-3 kHz without affecting responseat other frequencies. Variability between subjects may be +/−3 dB. Thisincludes variability due to variable insertions and movement of thetransducer with jaw movements. Variability across subjects may be +/−6dB. Even in low responding subjects may need to have adequate outputabove their thresholds at all frequencies. Subject based calibrationsmay likely be problematic for clinicians and best avoided if possible.

Output transducer assembly 30 may further comprise a number of otherexemplary specifications. For example, output transducer assembly 30 mayhave less than 1 percent harmonic distortion of up to 100 db SPL andless than 10 percent distortion of up to 106 db SPL. Output transducermay have less than 30 dB SPL noise equivalent pressure at the input.Output transducer may provide 15 dB of gain up to 1 kHz and 30 dB ofgain above 1 kHz.

I. Power Sources:

Both power and signal may be transmitted to the output transducerassembly 30. 1 uW of power into the ear may need to be generated to meetmaximum output specifications. Methods of transmitting power may includelight (photovoltaic), ultrasound, radio frequency, magnetic resonantcircuits.

In exemplary embodiments, a piezoelectric transducer driven by aphotovoltaic (PV) cell or a number of photovoltaic (PV) in placed inseries. The maximum voltage and current provided by the cells can belimited by the area and the amount of incident light upon them, 70 mWmay be a good upper limit for the amount of electrical power availablefor the output transducer at its maximum output. This power can belimited by the amount of heat that can be dissipated as well as batterylife considerations.

LEDs may be about 5% efficient in their conversion of electrical powerinto light power. The maximum light power coming out of the LEDs may benear 3.5 mW. The light coming out of the LED can cover a broader areathan the area of the photovoltaic cell. The broader area may be setbased on the movement of the ear canal and the ability to point thelight directly at the photovoltaic cells. For example, a spot with adiameter that is twice a wide as a square 3.16 mm×3.16 mm photocell maybe used. This spot size would have an area of 31.4 mm² (leading to anoptical efficiency of 32%). The photodetector area may comprise twoparts—one part to move the transducer in a first direction and anotherpart to move the transducer in a second direction, for example asdescribed in U.S. Pat. App. No. 61/073,271, filed on Jun. 17, 2008,entitled “OPTICAL ELECTRO-MECHANICAL HEARING DEVICES WITH COMBINED POWERAND SIGNAL ARCHITECTURES”, (attorney docket no. 026166-001800US), thefull disclosure of which is incorporated herein by reference. This twopart photodetector area may further reduce the efficiency by a factor oftwo to 16%. This efficiency may be improved depending on the result ofstudies showing how much the motion of the ear canal moves the light aswell as the ability to initially point the light down the ear canal.With a 16% efficiency, 560 uW of light power impinges on the surface ofeach of the two photovoltaics. The device may comprise at least onephoto detector, for example as described in U.S. Pat. App. No.61/071281, filed Jun. 17, 2008, entitled “OPTICAL ELECTRO-MECHANICALHEARING DEVICES WITH SEPARATE POWER AND SIGNAL COMPONENTS”, (attorneydocket no. 026166-001900US), the full disclosure of which isincorporated by reference.

FIG. 2 shows the sensitivity of silicon photovoltaics to differentwavelengths of light. The sensitivity of a photodetector is how muchcurrent is produced per unit power of incident light (A/W). In FIG. 2,maximum light intensity of 560 uW may be 336 uA at infrared wavelengths(S=0.6 A/W @ 900-1000 nm) or 224 uA in the “red” range (S=0.4 A/W @ 650nm). Red LEDs may be more efficient than infrared LEDs, so the increasedefficiency of the LEDs may overcome the decreased sensitivity of thephotodetector at those wavelengths. The maximum available currents maybe in the 220-340 uA range. The voltage characteristic of thephotodetector is set by the “diode” action of the junction. Starting a0.3 V, an increasingly non-linear voltage response may be encountered.Hence the maximum effective voltage of the photodetector for ourapplication may be 0.4V. Multiplying this 0.4V by the 224 uA one obtains90 uW. Taking this 90 uW and dividing by the 560 uW of light power ingives an efficiency of 16%. One may also use the photocells in series toincrease the amount of voltage available. However, the area of eachphotocell may need to be reduced to keep the total area the same. Thismay have the effect that voltage may be traded for current and viceversa, however the total amount of power remains fixed.

The LED/photovoltaic system may supply approximately 224 uA of currentand 0.4V. Voltage can be increased by putting cells in series but thevoltage increase may be at the proportional cost of current. 90 uW ofpower may be available to the transducer for producing motion of theeardrum. However, the amount of power utilized can depend on the loadcharacteristics. The optimal load may be a 1800 ohm resistor (0.4V/224uA). In either the piezoelectric case (capacitive load) or the voicecoil case (inductive load), the load impedance may change as a functionof frequency. A frequency at which this optimal impedance is matched maybe chosen. For the capacitive load case, the system may be currentlimited above this frequency and voltage limited below this frequency.For the inductive load case, the situation may reverse. In the currentlimited cases, one may not be able to reach the desired maximum outputlevels. In the voltage limited regions, driving the system too hard mayhighly distort the output. If 2 kHz is chosen as the optimal frequency,this impedance may correspond to a capacitance of 44 nF or an inductanceof 143 mH. Even with an optimal load attached, the overall efficiency ofthe optical power transfer is 0.04%. Yet even with this efficiency, theamount of power produced by the PV is 90× greater than what we expect toneed to input into the ear.

Table 1 below summarizes the above-mentioned exemplary powerspecifications.

TABLE 1 EXEMPLARY POWER SPECIFICATIONS FOR OUTPUT TRANSDUCER ParameterFormula Value Comment Input Power Maximum  70 mW May be chosen based onmagnetic system experience with head and battery life. LED efficiency  5% May be based on literature and experimental data Area ofillumination pR² R = 3.16 mm May be a reasonable guess based A = 31.4mm² on what will be required for robust illumination of photodetectorsArea of photodetectors $\frac{b^{2}}{2}$ B = 3.16 mm A = 5 mm² May bebased on what area of the eardrum is easily viewable from a mid earcanal location. Remember that only half of the area is available foreach photodetectors (hence the divide by 2). Optical efficiency$\frac{A_{illum}}{A_{pv}} \times 100\%$   16% Maximum optical powerE_(optical)E_(LED)P_(max) 560 mW incident on photodetectors Sensitivityof PV @ IR 0.6 A/W (~950 nm) Sensitivity of PV @ Red 0.4 A/W (~650 nm)Maximum PV current @ S_(PV)P_(λPV) 336 mA IR Maximum PV currentS_(PV)P_(λPV) 224 mA @ Red Maximum PV voltage 0.4 V Maximum voltage for~10% distortion. (0.3 V for ~1%) Maximum PV power @ V_(PVmax)I_(PVmax) 90 mW Red Optimal Load for PV $\frac{V_{PVmax}}{I_{PVmax}}$ 1800 ohmsOverall efficiency $\frac{P_{PV}}{P_{\max \bullet}} \times 100\%$0.13%

Other power transmission potions may include ultrasonic powertransmission, magnetic resonant circuits, and radiofrequency powertransmission. For magnetic resonant circuits, the basic concept is toproduce two circuits that resonant with each other. The “far” coilshould only draw enough power from the magnetic fields to perform itstask. Power transfer may be in the 30-40% efficient range.

II. Output Transducer Specifications

In exemplary embodiments, an output transducer may comprise two majorcharacteristics; the physics used to generate motion and the type ofreference method used. The choices for the physics used to generatemotion can include electromagnetic (voice coils, speakers, and thelike), piezoelectric, electrostatic, pryomechanical, photostrictive,magnetostrictive, and the like. Regardless of what physics are used togenerate motion, the energy of the motion can be turned into usefulmotion of the eardrum. In order to produce motion, forces or momentsthat act against the impedance of the eardrum may be generated. Togenerate forces or moments, the reaction force or moment is resisted. Toresist such forces or movements, a fixed anchor point may be introduced,a floating inertia may be used, for example, utilizing translational androtational inertia, or deforming an object so that the boundariesproduce a net force that moves the object, i.e., using a deformationtransducer.

FIG. 3 is a graph showing the mechanical impedance of the eardrum inrelation to that of various masses of 100 mg, 50 mg, 20 mg, and 10 mg.The impedance of the eardrum matches the masses of 100 mg, 50 mg, 20 mg,and 10 mg at frequencies of about 450 Hz, 700 Hz, 1.5 kHz, 3 kHz,respectively. The impedance of the mass can be dependent on the locationof the eardrum. By placing the mass away from the umbo, the impedancecan be decreased, for example halved, when the mass is positioned on theshort or lateral process of the malleus, for example. For example, amass of 40 mg can have an impedance at 1.5 kHz that is similar to a 20mg mass so as to match the impedance of the eardrum TM.

Exemplary physical specifications may be placed on the transducer basedon the size of the ear canal, the ability of an output transducer toremain in position and the perception of occlusion resulting from havinga mass present on the eardrum. Table 2 below show these specifications.

TABLE 2 EXEMPLARY PHYSICAL SPECIFICATIONS FOR OUTPUT TRANSDUCERParameter Value Comment Maximum dimension <5 mm If the dimension getslarger, then in plane with manipulating the transducer into annularplace may become difficult ligament of TM for physicians and may not fitdown some ear canals. Maximum dimension <2 mm If the dimension getslarger, then perpendicular to the anterior wall that “hangs” over TM theTM may begin to get in the way. Maximum mass 60 mg  A mass of 46 mg mayresult in significant “occlusion”. Other embodiments may be able to holdmore weight. There may be evidence that at even this weight gravity mayshift the position of the transducer depending on the orientation of thehead and the support to TM coupling.

Output transducer assembly 30 may use a piezoelectric element togenerate motion. Material properties of exemplary piezoelectric elementsare shown in the table 3 below.

TABLE 3 MATERIAL PROPERTIES OF EXEMPLARY PIEZOELECTRIC ELEMENTS TRS APCAPC APC APC single single disk bender Tapecast stacked STEMinc crystalcrystal Material APC 855 APC 850 APC PST 7 × 7 × .2 TRS APC 150 SMQAPMN-PT PMN-PT Density 7600 7700 8000 7900 7900 8200 (kg/m3) Curie 200360 155 250 166 Temperature k33 0.76 0.72 0.91 0.92 d31 276 175 290 1401000 930 (×10-12 m/V) d33 600 400 640 310 1900 2000 (×10-12 m/V) E33(N/m2) 5.10E+10 5.40E+10 5.56E+10 7.30E+30 1.16E+10 relative 3400 19005400 1400 7700 4600 dielectric constant (Er33) E11 (N/m2) 5.90E+106.30E+10 8.40E+10 2.48E+10 kp 0.68 0.63 0.58 0.92 kt 0.45 0.55 0.6 k310.4 0.36 0.34 0.51 0.72

III. Exemplary Output Transducers

Output transducer assembly 30 may comprise a piezoelectric based outputtransducer, for example, a transducer comprising a piezoelectricunimorph, piezoelectric bimorph, or a piezoelectric multimorph.Exemplary output transducers may comprise a simply supported bimorphbender 400 as shown in FIG. 4, a cantilevered bimorph bender 500 asshown in FIG. 5, a stacked piezo with mechanical multiplier 600 as shownin FIG. 6, a disk or narrow ring piezo with a mechanical multiplier 700as shown in FIG. 7 or a ring mass with bimorph piezoelectric transducer800 as shown in FIG. 8,

FIG. 4 shows a simply supported bimorph bender 400 suitable forincorporation with transducer assembly 30 as described above. Simplysupported bimorph bender 400 comprises a first mass 410 a, a second mass410 b, a bimorph piezoelectric cantilever 420, and a support 430.Cantilever 420 extends from a first end supporting first mass 410 a to asecond end supporting second mass 410 b. Cantilever 420 is coupled withthe support 430 comprising a protrusion 430 p extending from the supportto the transducer to couple the support to the transducer between thefirst and second ends. Support 430 may be configured to support thefirst and second masses 410 a, 410 b and the bimorph cantilever 420 onthe eardrum TM. For example, support 430 may comprise a mold shaped toconform with the eardrum TM, for example support 430 can be shaped withknown molding techniques. The portion 430 a of support 430 which is incontact with the fluid that couples to the eardrum TM can be flexible,for example, by comprising a flexible material such as silicone,flexible plastic, a gel, or the like. Other portions of support 430, forexample protrusion 430P may be rigid, for example, by comprising ametal, titanium, a rigid plastic, or the like. Simply supported bimorphbender 400 may comprise circuitry which receives an external, wirelesssignal and causes cantilever 420 to change shape. Cantilever 420 maypush against masses 410 a, 410 b causing a force on the masses 410 a,4101) in a direction 445 and also cause a force on support 430 in adirection 440 opposite direction 445. The force on support 430 drivesthe eardrum TM to produce sensations of sound.

FIG. 5A shows a cantilevered bimorph bender 500 suitable forincorporation with transducer assembly 30 as described above.Cantilevered bimorph bender 500 includes a mass 510, a bimorphcantilever 520 extending from mass 510, and a support 530 coupled withcantilever 520. Support 530 may be configured to support mass 510 andbimorph cantilever 520 on the eardrum TM, which may not be drawn toscale in FIG. 5A. For example, support 530 may comprise a mold shaped toconform with the eardrum TM. Cantilever 520 is coupled with the support530 comprising a protrusion 530p extending from the support to thetransducer. The portion 530 a of support 530 which is in contact withthe eardrum TM can be flexible, for example, by comprising a flexiblematerial such as silicone, flexible plastic, a gel, or the like. Otherportions of support 530 may be rigid, for example, by comprising ametal, titanium, a rigid plastic, or the like. Cantilevered bimorphbender 500 may comprise circuitry configured to receive an external,wireless signal and cause cantilever 520 to bend and thus push againstmass 510. The pushing action causes a force in a direction 545 on themass 510 and also a force on the support 530 in a direction 540 oppositethe direction 545. The force on the support 530 drives the eardrum TM toproduce sensations of sound.

Cantilevered bimorph bender 500 includes mass 510 and cantilever 520.Some embodiments may include more than one mass, cantilever, and/orsupport.

FIG. 5B shows cantilevered bimorph bender 550 suitable for incorporationwith transducer assembly 30 as described above. Bimorph bender 550includes a first mass 560 a and a second mass 560 b. A firstcantilevered bimorph 570 a is coupled to first mass 560 a. A secondcantilevered bimorph 570 b is coupled to second mass 560E). A support580 is coupled to the first cantilevered bimorph 570 a and secondcantilevered bimorphs 570 b. First cantilevered bimorph 570 a is coupledwith the support 580 comprising a protrusion 580 p. Second cantileveredbimorph 570 b is coupled with the support 580 comprising a protrusion580 pb. Support 580 may be configured to support masses 560 a, 560 b andbimorph cantilevers 570 a, 570 b on the eardrum TM, which may not bedrawn to scale on FIG. 5B. For example, support 580 may comprise a moldshaped to conform with the eardrum TM. The portion 580 a of support 580which is in contact with the eardrum TM can be flexible, for example, bycomprising a flexible material such as silicone, flexible plastic, agel, or the like. Other portions of support 580 may be rigid, forexample, by comprising a metal, titanium, a rigid plastic, or the like.Cantilevered bimorph bender 550 may comprise circuitry configured toreceive an external, wireless signal and cause cantilevers 570 a, 570 bto bend and thus push against masses 560 a, 560 b, respectively. Thepushing action causes force in a direction 595 on the masses 560 a, 560b and also a force on the support 580 in a direction 590 opposite thedirection 595. The force on the support 580 causes a translationalmovement which drives the eardrum TM to produce sensations of soundCantilevers 570 a, 570 b may push masses 560 a, 560 b in tandem to causesupport 540 to translate and drive the eardrum TM. Cantilevers 570 a,570 b may also push masses 560 a, 570 b in different orders as to causea rotational or twisting movement of the support 580 and the eardrum TM.

FIG. 6 shows a stacked piezo with mechanical multiplier 600 suitable forincorporation with transducer assembly 30 as described above. Thestacked piezo 600 comprises a plurality of piezoelectric elements or astacked piezoelectric array 610, mechanical multiplier 620, a mass 630,and a support 640. The piezoelectric array 610 may be held by mechanicalmultiplier 620. Mechanical multiplier 620 is coupled to mass 630 on side623 and support 640 on side 626. Mechanical multiplier 620 is coupledwith the support 640 comprising a protrusion 640 p extending from thesupport to the transducer. Support 640 may be configured to supportmechanical multiplier 620 and the piezoelectric array 610 and the mass630 on the eardrum TM, which may not be drawn to scale in FIG. 6. Forexample, support 640 may comprise a mold shaped to conform with theeardrum TM. The portion 630 a of support 630 which is in contact withthe eardrum TM can be flexible, for example, by comprising a flexiblematerial such as silicone, flexible plastic, a gel, or the like. Otherportions of support 640 may be rigid, for example, by comprising ametal, titanium, a rigid plastic, or the like. Stacked piezo 600 maycomprise circuitry configured to receive an external, wireless signaland cause the piezoelectric array 610 to expand or contract along axis650. Mechanical multiplier 620 uses leverage to multiply this expansionand contraction and change its direction to a direction along axis 655,thereby producing a force against mass -630 and support 640. The forceon support 640 drives the eardrum TM to produce sensations of sound.

FIG. 7 shows a narrow ring piezo with a mechanical multiplier 700suitable for incorporation with transducer assembly 30 as describedabove. The narrow ring piezo 700 comprises a piezoelectric ring 710,disc-shaped mechanical multiplier 720, a mass 730, and a support 740.Mechanical multiplier 720 is coupled to mass 730 and support 740.Mechanical multiplier 720 is coupled with the support 740 comprising aprotrusion 740 p extending from the support to the transducer. Support740 may be configured to support mechanical multiplier 720 and thepiezoelectric ring 710 and the mass 730 on the eardrum TM. For example,support 740 may comprise a mold shaped to conform with the eardrum TM.The portion 740 a of support 740 which is in contact with the eardrum TMcan be flexible, for example, by comprising a flexible material such assilicone, flexible plastic, a gel, or the like. Other portions ofsupport 740 may be rigid, for example protrusion 740P that extends tothe bimorph, by comprising a metal, titanium, a rigid plastic, or thelike. Mechanical multiplier 720 comprises a first side 723 and a secondside 726, the first side 723 extends inwardly from piezoelectric ring710 to mass 730 and the second side 726 extends inwardly frompiezoelectric ring 710 to support 740. Narrow ring piezo 700 maycomprise circuitry configured to receive an external, wireless signaland cause the piezoelectric ring 710 to expand or contract along axis750. Mechanical multiplier 720 uses leverage to multiply this expansionand contraction and change its direction to that along axis 755,producing a force against mass 730 and support 740. The force on support740 drives the eardrum TM to produce sensations of sound.

FIG. 8 shows a ring mass with bimorph piezoelectric transducer 800suitable for incorporation with transducer assembly 30 as describedabove. Piezoelectric transducer 800 comprises contact elements contactelements 815 and 818 to connect a washer ring 820 to a piezoelectricbimorph 810. Ring mass with bimorph piezoelectric transducer 800comprises a piezoelectric bimorph 810, contact elements 815, 818, awasher ring 820 which can serve as a mass and which defines an aperture825, and a support 830 coupled to the bimorph 810, the support 830coupled with bimorph 810 and passing through aperture 825 at least inpart. Bimorph 810 may comprise a single crystal bimorph. Support 830 maybe configured to support bimorph 810 on the eardrum TM. For example,support 830 may comprise a mold shaped to conform with the eardrum TM.The portion 830 a of support 830 which is in contact with the eardrum TMcan be flexible, for example, by comprising a flexible material such assilicone, flexible plastic, a gel, or the like. Other portions ofsupport 830, for example protrusion 830 p, may be rigid, for example, bycomprising a metal, titanium, a rigid plastic, or the like. Bimorph 810comprises a first end 813 and a second end 816. First end 813 and secondend 816 are respectively coupled to ring 820 through contact elements815 and 818, for example, through the use of an adhesive. Ring mass,withbimorph piezoelectric transducer 800 may be coupled to circuitryconfigured to receive an external, wireless signal and cause bimorph 810to flex in response. Flexion of bimorph 810 produces a shearing force orshear motion of first end 813 and second end 816 relative to washer ring820 and produces a translational force along axis 850 so as to drivesupport 830 against the eardrum TM, producing sensations of sound.

FIGS. 8A and 8B show a ring mass with bimorph piezoelectric transducer802 suitable for incorporation with transducer assembly 30 as describedabove. FIG. 8a shows a cross-sectional view of ring mass with bimorphpiezoelectric transducer 802. FIG. 8b shows a top view of ring mass withbimorph piezoelectric transducer 802. Bimorph 810 can be directlyconnected to washer ring 820 which can serve as a mass. Bimorph 810 iscoupled with a support 830 comprising a protrusion 830 p extending fromthe support to the transducer. Support 830 may be configured to supportwasher bimorph 810 and washer 820 on the eardrum TM. The portion ofsupport 830 which is in contact with the eardrum TM can be flexible, forexample, by comprising a flexible material such as silicone, flexibleplastic, a gel, or the like. Other portions of support 830 may be rigid,for example, the portions may comprise a metal, titanium, a rigidplastic, or the like. For example, support 830 may comprise a moldshaped to conform with the eardrum TM. Support 830 may be configured sothat protrusion 830 p is directly over the umbo UM. Ring mass withbimorph piezoelectric transducer 802 may comprise circuitry configuredto receive an external, wireless signal and cause bimorph 810 to bend orflex and thus push against washer 820. The pushing action causes a forcein a direction 852 on washer 820 and also a force on the support 830 ina direction 853. The force on the support 830 causes a translationalmovement of the umbo UM which can rotate malleus ML to producesensations of sound.

FIGS. 8B1 and 8B2 show perspective views of mass, for example a ringmass, with a piezoelectric transducer, for example a bimorphpiezoelectric transducer 803, in which the mass is coupled to thepiezoelectric transducer with a flexible intermediate structure, forexample intermediate element 815, suitable for incorporation withtransducer assembly 30 as described above. The flexible intermediatestructure can relax a boundary condition at the edge of thepiezoelectric transducer so as to improve performance of thepiezoelectric transducer coupled to the mass. Although an elongate rodis shown, the flexible intermediate structure may comprise many knownflexible shapes such as coils, spheres and leafs. Bimorph 810 isindirectly and flexibly connected to washer ring 820. The ends ofbimorph 810 can be directly connected to intermediate elements 815.Intermediate elements 815 can in turn be directly connected to washerring 820. Washer ring 820 can serve as a mass. The ends of bimorph 810may be rigidly attached to intermediate elements 815, for example, viaan adhesive or glue. Intermediate elements 815 may be rigidly attachedto intermediate elements 815, for example, via an adhesive or glue.Intermediate elements 815 is flexible so as to provide a flexibleboundary condition or a flexible connection between bimorph 810 andwasher ring 820. For example, intermediate elements 815 may comprise arod made of a flexible material such as carbon fiber or a similarcomposite material. Such a flexible material may be more prone totwisting than bending. By providing such a flexible boundary condition,the force outputted by transducer 803 can be greater, for example, twiceas great, as the force outputted if bimorph 810 were instead directlyand rigidly connected to washer ring 820.

Bimorph 810 is coupled with a support 830. Support 830 comprises aprotrusion 830P protruding from the bimorph 810 and a support member830E adapted to conform with the eardrum TM. Protrusion 830P is coupledto support member 830E. For example, protrusion 830P can comprise afirst magnetic member 83IP and support member 830E may comprise acomplementary second magnetic member 831E so that protrusion 830P andsupport member 830E are magnetically coupled. Both first magnetic member831 P and second magnetic member 831E may comprise magnets.Alternatively, one of first magnetic member 831P or second magneticmember 831E may comprise a magnet while the other comprises aferromagnetic material. To position transducer 803 on the eardrum TM,support member 830E may first be placed on the eardrum TM, followed bythe remainder of the transducer 803 as guided by first magnetic member831 P and second magnetic member 831E.

The use of magnetism to guide the positioning of transducer 803 canreduce a hearing professional's reliance on vision to positiontransducer 803 on the eardrum TM. 101381 Support member 830E maycomprise a mold shaped to conform with the eardrum TM. Support member830E can comprise a flexible material such as silicone, flexibleplastic, a gel, or the like. The portion of support member 830E incontact with protrusion 830P may be rigid, for example, the portions maycomprise a metal, titanium, a rigid plastic, or the like. Support 830may be configured so that protrusion 830P is directly over the umbo UM.Transducer 803 may also comprise circuitry 824. Circuitry 824 may beconfigured to receive an signal, for example, an external, wirelesssignal. Circuitry 824 can cause bimorph 810 to bend or flex and thuspush against washer 820. The pushing action causes a force in adirection 852 on washer 820 and also a force on the support 830 in adirection 853. The force on the support 830 causes a translationalmovement of the umbo UM which can rotate malleus ML to producesensations of sound.

FIGS. 8C and 8D show embodiments that comprise more than one bimorph,for example a ring mass dual bimorph piezoelectric transducer 804,suitable for incorporation with transducer assembly 30 as describedabove. Transducer 804 may comprise a mass from about 20 mg to about 60mg, for example about 40 mg. Ring mass with double bimorph piezoelectrictransducer 804 comprises first transducer, for example first bimorph 810a and second transducer, for example second bimorph 810 b. Malleus MLextends into the ear canal, and first bimorph 810 a and second bimorph810 b may extend along a line substantially perpendicular to malleus ML,or first bimorph 810 a and second bimorph 810 b may extend along a lineoblique to Malleus ML. Bimorph 810 a and bimorph 810 b are coupled to aring or washer 820 which comprises a mass. Bimorph 810 a and bimorph 810b are supported by support 830 comprising protrusions 830 pa and 830pb,which are coupled to bimorph 810 a and bimorph 810 b, respectively. Theportion of support 830 which is in contact with the eardrum TM can beflexible, for example, by comprising a flexible material such assilicone, flexible plastic, a gel, or the like. Other portions ofsupport 830 may be rigid, for example comprising a metal, titanium, arigid plastic, or the like. For example, support 830 may comprise a moldshaped to conform with the eardrum TM.

Ring mass with double bimorph piezoelectric transducer 804 may comprisecircuitry configured to receive an external, wireless signal and causebimorph 810 a and bimorph 810 b to bend and/or flex and thus pushagainst washer 820. The wireless signal may comprise a first signalconfigured to drive first bimorph 810 a and a second signal configuredto drive second bimorph 810 b. The pushing action of the firsttransducer in response to the first signal causes a first force in afirst direction 852 a on washer 820 and an opposite force on the support830 in an opposite direction 853 a. The pushing action of the secondtransducer in response to the second signal causes a second force in asecond direction 852 b on washer 820 and an opposite force on thesupport 830 in an opposite direction 853 b. The force on the support 830in first direction 853 a and second direction 853 b causes atranslational movement which drives the eardrum TM to produce sensationsof sound.

The dual transducer 804 allows the malleus to be driven in more than onedimension, for example with a first translational motion to rotate themalleus with hinged motion about the head of the malleus and secondrotational motion to twist the malleus about an elongate axis of themalleus extending from a head of the malleus toward the umbo. Whenbimorphs 810 a and 810 b are flexed at the same time and in the samedirection,'ring-mass-double-bimorph-piezoelectric-transducer 804 maywork similar to same asring-mass-double-bimorph-piezoelectric-transducer 804. However, flexionof bimorphs 810 a and 810 b at different times and/or in differentdirections or phase may produce a rotational twisting motion along theelongate axis of the malleus with support 830 and thus induce rotationat the umbo of eardrum TM. For example, the received external, wirelesssignal may cause only one of bimorph 810 a and bimorph 810 b to bend orflex. Alternatively or in combination, the received external, wirelesssignal may cause bimorph 810 a to bend or flex more than bimorph 810 b,or vice versa, so as to cause a rotational twisting motion of themalleus to occur along with the hinged rotation motion of the malleus totranslate the umbo of eardrum TM. Arrows 853TW show twisting motion ofthe malleus at umbo UM with a first rotation of the malleus about anelongate axis of the malleus. Arrows 853TR show translational motion ofthe umbo UM with hinged rotation of the malleus comprising pivoting ofthe malleus about the head of the malleus. The first transducer and thesecond transducer can be driven with a signal having a time delay, forexample a phase delay of 90 degrees, such that translation movement andtwisting of the malleus and umbo occur. Thus, a first portion support830 may translate in a first direction 853 and a second portion ofsupport 830 may translate in a second direction 853 b opposite firstdirection 853 a so as to rotate the malleus with twisting motion.

Thus, the first transducer and the second transducer comprising bimorphs810 a and 810 can be driven so as to cause translational movement and arotational movement of eardrum TM. Hinged rotational movement of themalleus to effect translational movement of the umbo UM may be made atlow frequencies less than about 5 kHz, for example frequencies less thanabout 1 kHz. Rotational twisting movement of the malleus may be made atfrequencies greater than about 2 kHz, for example high frequenciesgreater than 5 kHz.

FIG. 8E shows a plot of phase difference versus frequency for the firstand second transducers of the dual bimorph piezo of FIGS. 8C and 8D.This phase difference can result in increased frequency gain at highfrequencies above about 5 kHz, such that the user can hear the highfrequency sounds more clearly due to the twisting of the malleus. At afirst frequency below about 1 kHz, for example 0.5 kHz, the phasedifference between the first transducer and the second transducer issubstantially zero. At a second frequency above from about 3 to 6 kHz,for example above about 5 KHz, the phase difference between the firsttransducer and the second transducer is at least about 10 degrees. Forexample, at about 9 kHz, the phase difference between the firsttransducer and the second transducer may comprise about 100 degrees. Thephase difference between the first transducer and the second transducercan be provided in many ways, for example with the audio processor asdescribed above, configured to output a first channel to the firsttransducer and a second channel to the second transducer. The circuitrycoupled to the first transducer and the second transducer may beconfigured to provide the first signal phase shifted from the secondsignal in response to the audio signal, for example with circuitrycomprising at least one of a capacitor, a resistor or an inductorconfigured to provide a phase shift of the audio signal such that thefirst signal is phase shifted from the second signal.

FIG. 9 shows simply supported bimorph bender 400 housed in ahermetically sealed housing 900 suitable for incorporation withtransducer assembly 30 as described above. Housing 900 may comprise manyknown biocompatible materials. In many embodiments, an output transducermay comprise a hermetically sealed housing. Housing 900 may be rigidlyaffixed to masses 410 a and 410 b with rigid connections. First mass 410a is connecting to housing 900 with rigid connections 900RA1 and 900RA2.Second mass 410 b is connecting to housing 900 with rigid connections900RB1 and 900RB2. Housing 900 can provide additional mass for bimorph420 to push against. A rigid portion 430P of support 430 extends throughhousing 900 to bimorph 420. Hermitically sealed housing 900 may beconfigured for many of the above described transducers, for examplepiezoelectric at least one of cantilevered bimorph bender 500, 550,stacked piezo with mechanical multiplier 600, disk or narrow ring piezowith a mechanical multiplier 700, or transducer 800.

FIG. 9A shows an output transducer 902 which receives power throughoptical transmission suitable for incorporation with transducer assembly30 as described above. Output transducer 902 may comprise apiezoelectric transducer, a magnetostrictive transducer, aphotostrictive transducer, a coil and a magnet, or the like. As shown inFIG. 9A, output transducer 902 comprises a piezoelectric transducer 910which is coupled to annular mass 920. Piezoelectric transducer 910 andmass 920 are both supported by support 930. Piezoelectric transducer 910may comprise many of the piezoelectric elements described above, forexample at least one of a bimorph, a cantilevered bimorph, a stackedpiezo, or a disc or ring piezo. Mass 920 may be similar to many of themasses as previously discussed. Piezoelectric transducer 910 can bepowered by a photodetector 940 which receives light 945. Light 945 maycomprise a signal, for example, a signal representative of sound asdescribed above. Photodetector 940 can be coupled to circuitry 940 c.Circuitry 940 c can be supported with support 930, mass 920,piezoelectric transducer 930 and support 930. Circuitry 940 can becoupled to piezoelectric transducer 910 to convert light 945 into anelectrical signal which can cause piezoelectric transducer 910 to moveand cause vibrations on eardrum TM which may lead to a sensation ofsound. A housing 903 extends around piezoelectric transducer 910,circuitry 940 c, mass 920 and photodetector 940 to hermetically sealtransducer 902.

FIG. 98 shows an output transducer 904 which receives power throughmagnet and/or electric power transmission suitable for incorporationwith transducer assembly 30 as described above. Output transducer 904may comprise a piezoelectric transducer, a magnetostrictive transducer,a photostrictive transducer, a coil and a magnet, or the like. Outputtransducer 904 comprises a piezoelectric transducer 910 coupled to amass 920B. Piezoelectric transducer 910 and mass 920B are both supportedby support 930. Piezoelectric transducer 910 may comprise many of thepiezoelectric elements described above, for example at least one of abimorph, a cantilevered bimorph, a stacked piezo, or a disc or ringpiezo. Mass 920B may be similar to many of the masses as previouslydiscussed. Piezoelectric transducer 910 can be powered by an externalcoil 955 which produces a magnetic field 957 which causes a magneticfield 952 and a voltage in coil 950. Coil 950 is coupled to and powerspiezoelectric transducer 910. Coil 950 can be supported with mass 920B,transducer 910 and support 930. The electromagnetic field 957 producedby external coil 955 may provide a signal, for example, a signalrepresentative of sound, to coil 950. Appropriate variations in magneticfield 957 and magnetic filed 952 can cause piezoelectric transducer 910to cause vibrations on eardrum TM which may lead to a sensation ofsound.

Tables 4 and 5 below show characteristics of exemplary piezoelectricoutput transducers as described above, including simply supportedbimorph bender 400, cantilevered bimorph bender 500, stacked piezo withmechanical multiplier 600, disk or narrow ring piezo with a mechanicalmultiplier 700, and bimorph or wide ring piezo 800,

TABLE 4 EXEMPLARY PARAMETERS OF PIEZOELECTRIC OUTPUT TRANSDUCERSVariable Symbol Comments Displacement w Simply Supported Bimorph - Midspan at point of Cantilever Bimorph - Free end interest Stack - Free endNarrow Ring - Mid radius Wide Ring - Outer radius Beam or stack L lengthBeam or stack b Stack is assumed to have a square width Wide crosssection ring outer radius Wide ring a inner radius Thickness h Bimorph -½ total thickness Stack - single layer thickness Ring - total thicknessNumber of n Bimorph - number of layers in ½ thickness layers Stack -total number of layers Ring - total number of layers Piezoelectric d₁₁,d₃₃ constant Elastic moduli E₁₁, E₃₃ Density ρ Permittivity ∈_(o)8.854E−12 (F/m) of free space Relative ∈ ₃₃ permittivity Applied ΔVvoltage Applied F Simply Supported Bimorph - Force (N) at mid force spanCantilever Bimorph - Force (N) at free end Stack - Force (N) at free endNarrow Ring - Ring load (N/m) at mid radius Wide Ring - Ring load (N/m)at outer radius

TABLE 5 EXEMPLARY MECHANICAL FORMULAS FOR PIEZOELECTRIC OUTPUTTRANSDUCERS Type Formulas Comments Simply Supported Bimorph Bender 400${\begin{matrix}{{Displacement}\mspace{14mu} {per}\mspace{14mu} {Volt}} \\{\frac{w}{\Delta V} = {\frac{3}{16}{{nd}_{31}( \frac{L}{h} )}^{2}}} \\{Capacitance} \\{C = {2n^{2}ɛ_{0}{\overset{\_}{ɛ}}_{32}b\mspace{11mu} ( \frac{L}{h} )}} \\{Stiffness} \\{\frac{F}{w} = {32E_{11}b\mspace{11mu} ( \frac{h}{L} )^{2}}} \\{1^{st}\mspace{14mu} {Mechanical}\mspace{14mu} {Resonance}} \\{f_{1} = {\frac{(\pi)^{2}}{2\; \pi}\sqrt{\frac{E_{11}h^{2}}{3\; \rho \; L^{4}}}}}\end{matrix}\quad}\quad$ Cantilevered Bimorph Bender 500 $\begin{matrix}{{Displacement}\mspace{14mu} {per}\mspace{14mu} {Volt}} \\{\frac{w}{\Delta V} = {\frac{3}{4}{{nd}_{31}( \frac{L}{h} )}^{2}}} \\{Capacitance} \\{C = {2n^{2}ɛ_{0}{\overset{\_}{ɛ}}_{32}b\mspace{11mu} ( \frac{L}{h} )}} \\{Stiffness} \\{\frac{F}{w} = {2E_{11}b\mspace{11mu} ( \frac{h}{L} )^{2}}} \\{1^{st}\mspace{14mu} {Mechanical}\mspace{14mu} {Resonance}} \\{f_{1} = {\frac{(1.875)^{2}}{2\; \pi}\sqrt{\frac{E_{11}h^{2}}{3\; \rho \; L^{4}}}}}\end{matrix}\quad$ Stac (shown with displacement amplifier) 600$\begin{matrix}{{Displacement}\mspace{14mu} {per}\mspace{14mu} {Volt}} \\{\frac{w}{\Delta V} = {nd}_{32}} \\{Stiffness} \\{\frac{F}{w} = \frac{E_{32}B^{2}}{L}} \\{Capacitance} \\{C = \frac{{nɛ}_{0}{\overset{\_}{ɛ}}_{32}b^{2}}{h}} \\{1^{st}\mspace{14mu} {Mechanical}\mspace{14mu} {Resonance}} \\{f_{1} = {\frac{1}{4L}\sqrt{\frac{E_{32}}{\rho}}}}\end{matrix}\quad$ The 1^(st) mechanical resonance equation may be the1/4 wave “rod” resonance which can tend to be very high. This may not bethe first resonance of the system. The most likely 1^(st) mode may bethe mass of the piezo/ref mass in conjunction with the spring of thedisplacement amplifier or some kind of bending mode. Narrow Ring (shownwith displacement amplifier) 700 $\begin{matrix}{{Displacement}\mspace{14mu} {per}\mspace{14mu} {Volt}} \\{\frac{w}{\Delta V} = {{nd}_{31}\mspace{14mu} ( \frac{r_{0}}{h} )}} \\{Stiffness} \\{\frac{F}{w} = \frac{E_{11}t}{r_{o}( \frac{h}{r_{o}} )}} \\{Capacitance} \\{C = {n^{2}ɛ_{0}{\overset{\_}{ɛ}}_{32}2\; {\pi t}\mspace{14mu} ( \frac{r_{o}}{h} )}} \\{1^{st}\mspace{14mu} {Mechanical}\mspace{14mu} {Resonance}}\end{matrix}\quad$ Remember for ring cases that F is a ring load (N/m)that will be summed by the displacement amplifier. The appropriate1^(st) mechanical resonance mode may not be clear. Likely the firstresonance may either be a bending type mode or a cos(2θ) mode. Wide Ring$\begin{matrix}{{Displacement}\mspace{14mu} {per}\mspace{14mu} {Volt}} \\{\frac{w}{\Delta V} = {{nd}_{31}\mspace{14mu} ( \frac{b}{h} )}} \\{Stiffness} \\{\frac{F}{w} = {\frac{E_{11}t}{b}\frac{( {b^{2} - a^{2}} )}{{( {1 + v} )a^{2}} + {( {1 - v} )b^{2}}}}} \\{Capacitance} \\{C = {n^{2}ɛ_{0}{\overset{\_}{ɛ}}_{32}\frac{\pi ( {b^{2} - a^{2}} )}{h}}} \\{1^{st}\mspace{14mu} {Mechanical}\mspace{14mu} {Resonance}}\end{matrix}\quad$

FIG. 10 shows an output transducer assembly comprising 1000 acantilevered bimorph bender positioned on a support 1010 such that theoutput transducer assembly is positioned over the lateral process andaway from the umbo when the support is placed on the eardrum, suitablefor incorporation with transducer assembly 30 as described above. Manyof the output transducers as described above can be positioned onsupport 1010 so as to couple to the umbo of the eardrum TM with thetransducer positioned away from the umbo, for example on the lateralprocess LP. The output transducer positioned on the support 1010 so asto couple to the umbo with the transducer positioned away from the umbomay comprise at least one of a piezoelectric transducer, arnagnetostrictive transducer, a photostrictive transducer, a coil or amagnet. Support 1010 can be made with known methods of molding tomanufacture a support customized to the ear of the user, for example aswith the known EarLens. The transducers as described above, for examplesimply supported bimorph bender 400, cantilevered bimorph bender 500,cantilevered bimorph bender 550, stacked piezo with mechanicalmultiplier 600, ring piezo with mechanical multiplier 700 and ring masswith bimorph piezoelectric transducer 800 can be positioned on support1010 so as to position the transducer at the desired location on theeardrum when support 1010 is placed against tympanic membrane TM. Asshown in FIG. 10, the transducer may comprise cantilevered bimorphbender 500 on support 1010 and coupled to eardrum TM over the lateralprocess LP and away from the umbo UM. Cantilevered bimorph bender 500can be placed on the support so as to align with malleus ML when thesupport is placed against the eardrum. For example, support 530 ofcantilevered bimorph bender 500 can be positioned on support 1010 toconform to the portion of the eardrum TM over the lateral process LPwhen support 1010 is placed against the eardrum TM. In some embodiments,support 530 can be placed directly on the eardrum without support 1010,for example directly over the lateral process LP. Mass 510 ofcantilevered bimorph bender 500 may be placed along the eardrum awayfrom the umbo U of the eardrum TM so as to decrease a mechanicalimpedance of the support to sound transmitted with the eardrum TM.Cantilever 520 has a first end coupled to mass 510 and a second endcoupled to support 530. Cantilever 520 may bend and push against mass510 and cause a force on support 530 which drives the lateral process LPof the malleus ML to produce sensations of sound.

FIGS. 10A and 10B show an output transducer assembly 1050 suitable forincorporation with transducer assembly 30 as described above andcomprising cantilevered bimorph bender 500 placed on a support 1060which may be made from a mold of the user's ear. The output transducerpositioned on the support 1060 may comprise at least one of apiezoelectric transducer, a magnetostrictive transducer, aphotostrictive transducer, a coil or a magnet. Support 530, mass 510 andthe elongate member comprising bimorph cantilever 520 of bimorph bender500 are positioned on support 1060 such that mass 510 is positioned awayfrom the umbo and the elongate member is coupled to the umbo whensupport 1060 is placed against eardrum TM. The elongate member, forexample bimorph cantilever 520, extends from the mass supported on thelateral process to the umbo so as to couple to the motion of thetransducer to the eardrum at the umbo. This configuration has theadvantage of lowering the mechanical impedance with the mass positionedaway from the umbo while providing mechanical leverage with coupling atthe umbo.

The mass can be positioned away from the umbo and/or aligned with themalleus ML in many ways so as to reduce the input impedance of thetransducer assembly. For example, mass 510 can be positioned on support1060 such that mass 510 is supported with the lateral process LP whensupport 1060 is placed against the ear. Also cantilevered bimorph bender500 and support 530 can be placed directly on the eardrum TM such thatmass 510 is aligned with malleus ML, for example aligned with lateralprocess LP. As shown in FIGS. 10A and 10B, mass 510 is placed on support1060 over the lateral process LP and support 530 is placed on support1060 over the umbo U when support 1060 is placed against the eardrum TM.The elongate member comprising bimorph cantilever 520 has a first endcoupled to mass 510 and a second end coupled to support 530. Cantilever520 may bend and push against mass 510 and cause a force on support 530which drive the tip T of the malleus ML to produce sensations of sound.The length of cantilever 520 may be provided with a longer length suchthat cantilever 520 can provide more mechanical leverage while reducingthe input impedance of mass 510.

FIG. 11 shows two or more transducers positioned on a support 1130 so asto rotate the malleus with hinged rotation at low frequencies and twistthe malleus at high frequencies and suitable for incorporation withtransducer assembly 30 as described above. Many of the above describedtransducers can be placed on support 1130. For example, embodiments ofcantilevered bimorph bender 550 and bimorph or wide ring piezo 800 maycause a twisting motion on the eardrum TM and thus the malleus ML.Placement of two or more output transducers, on different parts of theeardrum TM can also produce a rotational or twisting motion on theeardrum TM at the umbo and the malleus ML. The placed output transducersmay comprise, for example, at least one of simply supported biomorphbender 400, cantilevered biomorph bender 500, stacked piezo withmechanical multiplier 600, disk or narrow ring piezo with a mechanicalmultiplier 700, and biomorph or wide ring piezo 800. For example, FIGS.11 and 11A show two cantilevered bimorph benders 500A and 5008Bconfigured to couple to the umbo of the eardrum TM on opposite lateralsides over the tip T of malleus ML. Cantilevered bimorph benders 500Aand 500B each comprise masses 510A and 510B, respectively, and bimorphcantilevers 520A and 520B, respectively, and may both be supported witha common support 530 and/or support 1130 which also supports masses 510Aand 510B. Each of bimorph cantilevers 520A and 520B comprises anelongate member that extends from the mass to the umbo to couple to theeardrum at the umbo. A phase difference, as described above, betweenbimorphs 500A and 500B may cause malleus ML to twist. Masses 510A and510B are positioned on support 1130 such that masses 510A and 5108 aresupported with the lateral process when support 1130 is placed againsteardrum TM. Output transducers may be placed on other areas of theeardrum TM as well, for example at additional locations away from theumbo as described above. In some embodiments, support 530 can be coupleddirectly to eardrum TM, for example without support 1130.

Many of the above embodiments can be evaluated on an empirical number ofpatients, for example 10 patients to optimize the transducers, forexample transducer mass, positioning, support and circuitry. Forexample, experiments can be conducted on an empirical number of tenpatients to determine improved coupling of sound with differentialmovement of the first transducer and second transducer. In addition totesting with patients, the embodiments can be tested with computersimulations and laboratory testing. The below described experiments aremerely examples of experiments that can be performed, and a person ofordinary skill in the art will recognize many variations andmodifications that can be used to improve and optimize the performanceof the transducer devices described herein.

IV. Experimental

For exemplary piezoelectric elements, five key characteristics werelooked at as a function of geometric parameters. The five parameterswere: 1) minimum manufacturable layer thickness, 2) electricalcapacitance, 3) 1^(st) mechanical resonant frequency (if available), 4)low frequency stiffness, and 5) maximum displacement achievable with aphotodetector power source. For each exemplary piezoelectric element, acontour plot of the maximum displacement achievable at 2 kHz was made.FIG. 12 shows an exemplary contour map for an embodiment of aback-to-back amplified stack piezoelectric elements, a PZT506back-to-back stack with displacement amplifier. Similar plots can bemade for additional embodiments comprising the simply supported bimorphpiezoelectric elements, for example a PZT506 simply supported bimorph, aTRS singly crystal simply supported bimorph, and a PVDF simply supportedbimorph piezoelectric elements. FIG. 12 includes combinations ofdifferent numbers of photodetectors used to power the piezoelectricelement and the width of the piezoelectric element. The displacementshown accounts for the electrical limitations of the photovoltaic powersource as well as any mismatch between the impedance of the umbo and thestiffness of the driving piezo. Equation 1 and Table 6 below show theequation for the maximum displacement and the parameter definitions.

$\begin{matrix}{d_{m\; {ax}} = {( \frac{d}{V} ){R( \frac{K_{pz}}{K_{pz} + {R^{2}Z_{umbo}}} )}{{\min( {{N_{PD}V_{{ma}\; x}},\frac{( \frac{I_{{ma}\; x}}{N_{PD}} )}{2\pi \; f_{1}C}} )}.}}} & {{EQUATION}\mspace{14mu} 1}\end{matrix}$

TABLE 6 EXEMPLARY TEST PARAMETERS Parameter Value f_(max) Maximumfrequency of interest (10 kHz) f₁ 2 kHz - frequency used to optimizedesign R Lever ratio K_(pz) Low frequency stiffness of piezo Z_(umbo)Impedance of umbo at f₁ d Displacement per volt of a given design VN_(PD) Number of photocells in series V_(max) Maximum voltage of singlephotocell (0.4 V) I_(max) Maximum current of single photocell given theillumination constraints (224 uA) C Capacitance of a given design min(x,y) Minimum function which takes the minimum of the two arguments (x, y)

On top of the contour map shown, other parameters are shown as“constraint lines”. For example, the minimum manufacturable thickness isrepresented as a line. Any design point falling below or to the right ofthis line may be achievable. Any design point falling above or to theleft calls for a layer thickness that is not currently available fromany of the contacted vendors. Often, only integer numbers of layers arepossible. Similarly, the capacitance is shown in a line. Any designfalling below or to the right of this line has less than the optimalcapacitance for 2 kHz. Any design above or to the left has a highercapacitance. At this point, one must remember that the displacementcontours are shown at 2 kHz. At different frequencies, there will be adifferent optimal capacitance. (Optimizing for higher frequencies willrequire smaller capacitances.) Designs that have a mechanical resonanceof 10 kHz are shown as a line. Designs to the right have higher resonantfrequencies; designs to the left have lower resonant frequencies.Designs that have a low frequency stiffness equal to the umbo stiffnessat 10 kHz are shown with a line. Designs to the right have higherstiffnesses; designs to the left have lower stiffnesses. In exemplaryembodiments, piezoelectric element parameters that are below and to theright of all the constraint lines while at the same time maximizinglocation on the displacement contour are chosen. Contour maps can bemade for embodiments of bimorph piezoelectric transducers using theparameters set forth in Table 7.

TABLE 7 EXEMPLARY TEST PARAMETERS FOR BIMORPH PIEZOELECTRICS TRS -Single Parameter PZT506 Crystal PVDF d ₁₁ 64.5 GPa 11.6 GPa 3.0 GPa d₃₃225 pm/V 1000 pm/V 20 pm/V ∈ ₃₃ 2250    7700    12   ρ 8000 Kg/m³ 7900Kg/m³ 1780 Kg/m³ Minimum layer 20 um 140 um 2 um thickness Lever Ratio1.0 1.0 1.0 L 5 mm 5 mm 5 mm

Contour maps can be made for embodiments of simply supported bimorphpiezoelectrics using the parameters set forth in Table 8. The bimorphwith the greatest displacement that meets all of the constraints may beselected. Exemplary embodiments SSBM1, SSBM2, SSBM3, SSBM4, SSBM5,SSBM6, SSBM7, SSBM8, SSBM12, SSBM15, and SSBM18 give displacementsgreater than 0.1 um at 2 kHz.

TABLE 8 DISPLACEMENT MEASUREMENTS FOR EXEMPLARY BIMORPH PIEZOELECTRICEMBODIMENTS Beam Number of Beam ½ Number of Layer Maximum EmbodimentMaterial width photodetectors thickness layers thickness displacementSSBM1 PZT506 0.5 mm 1 120 um 6 20 um 0.15 um SSBM2 PZT506 0.5 mm 2 120um 4 30 um 0.16 um SSBM3 PZT506 0.5 mm 3 120 um 3 40 um 0.15 um SSBM4PZT506 1.0 mm 1 100 um 4 25 um 0.15 um SSBM5 PZT506 1.0 mm 2 100 um 2 50um 0.15 um SSBM6 PZT506 1.0 mm 3 100 um 1 100 um 0.12 um SSBM7 PZT5061.5 mm 1 100 um 3 33 um 0.12 um SSBM8 PZT506 1.5 mm 2 100 um 2 50 um0.14 um SSBM9 PZT506 1.5 mm 3 100 um 1 100 um 0.09 um SSBM10 TRS-SC 0.5mm 1 280 um 2 140 um 0.045 um SSBM11 TRS-SC 0.5 mm 2 280 um 2 140 um0.09 um SSBM12 TRS-SC 0.5 mm 3 280 um 2 140 um 0.13 um SSBM13 TRS-SC 1.0mm 1 280 um 2 140 um 0.05 um SSBM14 TRS-SC 1.0 mm 2 280 um 2 140 um 0.09um SSBM15 TRS-SC 1.0 mm 3 230 um 1 230 um 0.10 um SSBM16 TRS-SC 1.5 mm 1280 um 2 140 um 0.045 um SSBM17 TRS-SC 1.5 mm 2 230 um 1 230 um 0.07 umSSBM18 TRS-SC 1.5 mm 3 230 um 1 230 um 0.10 um SSBM19 PVDF 2.0 mm 2 210um 34 6.2 um 0.045 um SSBM20 PVDF 2.0 mm 3 210 um 16 13.1 um 0.045 umSSBM21 PVDF 3.0 mm 2 210 um 27 7.8 um 0.04 um SSBM22 PVDF 3.0 mm 3 210um 14 15 um 0.04 um

The PZT506 material appears to be the suitable for making the bimorph.Its combination of thin layer thicknesses, high piezoelectric constantsand moderate permittivity provides a suitable best output. Also, itappears that a wide range of beams all produce roughly the same output,0.15 um. Choosing between these options can be based on tradeoffs ofmanufacturing. For example, layers in the biomorph can be traded-offagainst segmenting the photodetector.

Contour maps can be made for embodiments of back-to-back amplified stackpiezoelectric elements, a TRS single crystal back-to-back stack withdisplacement amplifier, respectively. A displacement amplified stackpiezoelectric elements may comprise a scissor jack with two stacksplaced back-to-back pushing outwards. In this configuration, thecenterline of the assembly does not move. Therefore, the maximum stacklength to consider for displacement purposes is 2.5 mm or half of themaximum allowable dimension. However, the effective capacitance may beneeded to account for both stacks. The lever ratio may be limited to bebetween 1 and 15. In between those limits, the stiffness of the stackcan be matched to the impedance of the umbo at 10 kHz. Since the numberof layers in a stack is high, the thickness of the glue/electrodesbetween layers may need to be considered. For example, a glue/electrodelayer thickness of 16 um may be used. Like with simply supported bimorphpiezoelectric elements above, amplified stack piezoelectric elementswere analyzed at a variety of thicknesses and assuming various numbersof photodetectors in series. Neither the stiffness nor the 1^(st)resonance of the stack was a limiting factor while layer thickness,capacitance and length may be limiting factors.

Table 9 below shows some exemplary ranges of parameters for embodimentsof back-to-back amplified stack piezoelectric elements.

TABLE 9 EXEMPLARY TEST PARAMETERS FOR BACK- TO-BACK STACK PIEZOELECTRICSTRS - Single Parameter PZT506 Crystal E₁₁ 64.5 GPa 11.6 GPa d₃₃ 545 pm/V1900 pm/V ∈ ₃₃ 2250 7700 ρ 8000 Kg/m³ 7900 Kg/m³ Minimum layer 20 um 140um thickness Lever Ratio 1.0 to 15.0 1.0 to 15 L 2.5 mm 2.5 mm

Table 10 below shows parameters for several embodiments of back-to-backamplified stack piezoelectric elements Both the single crystal materialand the PZT506 material appear to have maximum outputs near 0.3 um.Several embodiments of back-to-back amplified stack piezoelectricelements produce similar amounts of displacement. Thus, there may beflexibility in manufacturing.

TABLE 10 DISPLACEMENT MEASUREMENTS FOR EXEMPLARY BACK- TO-BACK STACKPIEZOELECTRIC EMBODIMENTS Number of Stack photode- Number of LayerMaterial width tectors layers thickness Maximum PZT506 0.5 mm 1 65 20 um0.2 um PZT506 0.5 mm 2 45 40 um 0.23 um PZT506 0.5 mm 4 25 90 um 0.28 umPZT506 0.75 mm 1 58 30 um 0.15 um PZT506 0.75 mm 2 32 65 um 0.18 umPZT506 0.75 mm 4 16 135 um 0.20 um PZT506 1.0 mm 1 45 40 um 0.13 umPZT506 1.0 mm 2 25 70 um 0.15 um PZT506 1.0 mm 4 12 180 um 0.16 umTRS-SC 0.5 mm 1 17 140 um 0.1 um TRS-SC 0.5 mm 2 17 140 um 0.2 um TRS-SC0.5 mm 4 14 170 um 0.31 um TRS-SC 0.75 mm 1 17 140 um 0.14 um TRS-SC0.75 mm 2 17 140 um 0.28 um TRS-SC 0.75 mm 4 9 260 um 0.31 um TRS-SC 1.0mm 1 17 140 um 0.15 um TRS-SC 1.0 mm 2 14 175 um 0.25 um TRS-SC 1.0 mm 47 350 um 0.28 um

Embodiments of piezoelectric elements were also tested using a laservibrometer to measure the velocity (and hence the displacement) of atarget. Data was analyzed to yield displacement per volt and plottedversus frequency. Data was determined using the equations mentionedabove and plotted alongside the test data.

A single Morgan stacked as shown in FIG. 13A was tested. The parametersfor the single Morgan stack piezo are shown in Table 11 below. A plot ofthe test data, including displacement versus voltage, is shown in FIG.13B.

TABLE 11 EXEMPLARY PARAMETERS FOR MORGAN STACKED PIEZO Parameter ValueMaterial Morgan PZT506 Piezo Dimensions 1 × 1 × 1.8 mm Layer Thickness20 μm Number of Layers 50 E11 6.45e10  d33 545e−12 d31 −225e−12  Density8000 Relative Permittivity 2250 Kp (coupling factor) 0.70 Input Voltage1 V Input Frequency range 100-20000 Hz Measured capacitance 52 nFCalculated capacitance 49.8 nF

A Steiner and Martins cofired Piezo series bimorph as shown in FIG. 14Awas tested. The parameters for the single Morgan stack are shown inTable 12 below. A plot of the test data, including displacement versusvoltage, is shown in FIG. 14B. Affixing the piezo using a flexiblematerial increased the vibrational displacement by a few dB.

TABLE 12 EXEMPLARY PARAMETERS FOR STEINER AND MARTINS COFIRED PIEZO -SERIES BIMORPH Parameter Value Material STEMInc SMQA Piezo Dimensions 7mm × 7 mm Layer Thickness 200 μm E11 8.6e10  d33 310e−12 d31 −140e−12 Density 7900 Relative Permittivity 1400 Kp (coupling factor) 0.58 InputVoltage 1 V Input Frequency range 100-20000 Hz Measured capacitance 1.4nF Calculated capacitance 1.4 nF

A TRS Single Crystal Bimorph Cantilever as shown in FIG. 15A was tested.The parameters for the single Morgan stack are shown in Table 13 below.The parameters may comprise known parameters and can be measured by oneof ordinary skill in the art. A plot of the test data, includingdisplacement versus voltage, is shown in FIG. 15B.

TABLE 13 EXEMPLARY PARAMETERS FOR TRS SINGLE CRYSTAL BIMORPH CANTILEVERParameter Value Material TRS single crystal Piezo Dimensions 6 mm × 6 mmLayer Thickness 140 μm E11 1.16e10  d33 1900e−12 d31 −1000e−12  Density7900 Relative Permittivity 7700 Input Voltage 1 V Input Frequency range100-20000 Hz Measured capacitance nF Calculated capacitance 35 nF

A TRS Single Crystal Bimorph on a washer as shown in FIG. 16A wastested. The parameters for the single Morgan stack are shown in Table 14below. A plot of the test data, including displacement versus voltage,is shown in FIG. 16B In this test, the resonance is in the predictedfrequency but the magnitude is off by nearly 20 dB. The capacitance isalso off, so the piezo may be damaged.

TABLE 14 EXEMPLARY PARAMETERS FOR TRS SINGLE CRYSTAL ON WASHER ParameterValue Material TRS single crystal Piezo Dimensions 1 mm × 5 mm LayerThickness 140 μm E11 1.16e10  d33 1900e−12 d31 −1000e−12  Density 7900Relative Permittivity 7700 Input Voltage 1 V Input Frequency range100-20000 Hz Measured capacitance 3.6 nF Calculated capacitance 4.2 nF

A stacked piezo pair with V-jack type displacement amplification asshown in FIG. 17A was tested. The parameters for the single Morgan stackare shown in Table 15 below. A plot of the test data, includingdisplacement versus voltage, is shown in FIGS. 17B and 17C. In thistest, an additional resonance appears which may most likely a resonancein the mechanical lever.

TABLE 15 EXEMPLARY PARAMETERS FOR STACKED PIEZO PAIR WITH V-JACKDISPLACEMENT AMPLIFICATION Parameter Value Material Morgan PZT506 PiezoDimensions 1 × 1 × 3.6 mm Lever angle, lever ratio 3.5°, 16X LayerThickness 20 μm Number of Layers 100 E11 6.45e10  d33 545e−12 d31−225e−12  Density 8000 Relative Permittivity 2250 Kp (coupling factor)0.70 Input Voltage 1 V Input Frequency range 100-20000 Hz Measuredcapacitance 104 nF Calculated capacitance 99.6 nF

Embodiments of output transducers which were placed on a subject'seardrum were tested. The transducer was wire driven, connected directlyto the audiometer to determine the acoustic threshold. In order toreduce the effect of the wires, 48 AWG wire was used between thetransducer and a location just outside the ear canal. The position ofthe transducer was verified by a physician using a video otoscope.

Once in place, the audiometer driven transducer was energized across a12 kΩ load and the audiometer setting adjusted to reach threshold. Thethreshold was recorded at each frequency tested. After the testing wascomplete and the transducer removed from the subject's ear, thetransducer was reconnected to the audiometer and the voltage measured.Often, the audiometer setting was increased by 40 dB to make a reliablemeasurement.

The data collected was converted to pressure equivalent using MinimumAudible Pressure curves and plotted against the specifications,bench-top data and average electromagnetic or EM system output. In allcases, the assumption is that the input to the transducer is 0.4V peakand 75 mW. The bench-top data was determined by measuring the unloadeddisplacement and comparing to the known displacement of the umbo at eachfrequency plotted.

In addition to the threshold measurements, the feedback pressure wasmeasured at two locations: at the umbo and at the entrance to the earcanal. Often, the transducer was driven by a laptop running SYSid, andoperated at 1V peak, with the feedback measured with an ER-7cmicrophone. The resulting data gives a measure of the gain margin foreach transducer design/location if the microphone is located either deepin the canal or at the canal entrance.

FIGS. 18A-20B show peak power output and feedback for the testedembodiments of output transducers. Although an idealized target peakpower output of 106 dB is shown for purposes of comparison, peak poweroutputs of less than 106 dB, for example 80 or 90 dB at 10 kHz, canprovide improved hearing for many patients. FIGS. 18A and 18B show peakpower output and feedback, respectively, of a TRS single crystal bimorphplaced on the umbo. The on ear results match the bench top predictionsup to 2 kHz, then diverge, with the on-ear results remaining flat up to12 kHz. The umbo located transducer used a different piezo than thecenter of pressure located transducer.

FIGS. 19A and 19B show peak power output and feedback, respectively, ofa TRS single crystal bimorph placed on the center of pressure of theeardrum. The on ear results match the bench top predictions up to 2 kHz,then diverge, with the on-ear results remaining flat up to 12 kHz.Employing feedback cancellers or other feedback handling techniques, ormoving the microphone location can improve the power output and feedbackprofiles.

FIGS. 20A and 20B show peak power output and feedback, respectively, ofa stacked piezo pair with V-jack type displacement amplification placedon the center of pressure of the eardrum. The 100 nF piezo load causesthe PV system to be current limited starting at a low frequency. Theoverall equivalent pressure per volt (when not current limited) isbetter than the bimorph case by about 20 dB.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting in scope of the invention which is defined by the appendedclaims.

1.-65. (canceled)
 66. A method of transmitting an audio signal to auser, the user having an ear comprising an eardrum, the methodcomprising: supporting a mass and a piezoelectric transducer with asupport on the eardrum of the user; driving the support and the eardrumwith a first force and the mass with a second force, the second forceopposite the first force.
 67. The method of claim 66 wherein the earcomprises a mechanical impedance and wherein the mass, the piezoelectrictransducer and the support comprise a combined mechanical impedance andwherein the combined mechanical impedance matches the mechanicalimpedance of the eardrum for at least one audible frequency within arange from about 1 kHz to about 6 KHz.
 68. A method of transmitting anaudio signal to a user, the user having an ear comprising an eardrum,the method comprising: supporting circuitry and a transducer coupled tothe circuitry with the eardrum; and transmitting the audio signal with awireless signal to the circuitry to drive the transducer in response tothe audio signal.
 69. A method of transmitting an audio signal to auser, the user having an ear comprising an eardrum having a mechanicalimpedance, the method comprising: supporting a transducer and a supportcoupled to the eardrum with the eardrum, wherein a combined mass of thesupport and the transducer supported thereon matches the mechanicalimpedance of the eardrum for at least one audible frequency betweenabout 0.8 kHz and about 10 kHz.
 70. A method of transmitting an audiosignal to a user, the user having an ear comprising an eardrum and amalleus connected to the ear drum at an umbo, the method comprising:supporting a transducer with a support positioned on the eardrum;vibrating the support and the eardrum with the transducer positionedaway from the umbo.
 71. The method of claim 70 wherein a first movementof the transducer is decreased relative to a second movement of the umbowhen the eardrum is vibrated and wherein the second movement of the umbois amplified relative to the first movement of the transducer.
 72. Amethod of transmitting an audio signal to a user, the user having an earcomprising an eardrum and a malleus connected to the eardrum at an umbo,the method comprising: supporting a first transducer and a secondtransducer with a support positioned on the eardrum; and driving thefirst transducer and the second transducer in response to the audiosignal to the twist the malleus such that the malleus rotates about anelongate longitudinal axis of the malleus.